As filed with the Securities and Exchange Commission on January 29, 2026

Registration No. 333-290947

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Amendment No. 4

to

FORM S-1

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

RF Acquisition Corp III

(Exact name of registrant as specified in its charter)

RF Acquisition Corp III

111 Somerset Road, #05-07

Singapore, 238164

Tel: +65 6904 0766

(Address, including zip code, and telephone number, including area code, of registrant’s principal executive offices)

Winston & Strawn LLP

800 Capitol Street

Suite 2400

Houston, Texas 77002

Tel: (713) 651-2600

(Name, address, including zip code, and telephone number, including area code, of agent for service)

Copies to:

Approximate date of commencement of proposed sale to the public: As soon as practicable after the effective date of this registration statement.

If any of the securities being registered on this Form are to be offered on a delayed or continuous basis pursuant to Rule 415 under the Securities Act of 1933 check the following box. ☐

If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, please check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. ☐

If this Form is a post-effective amendment filed pursuant to Rule 462(c) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. ☐

If this Form is a post-effective amendment filed pursuant to Rule 462(d) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. ☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 7(a)(2)(B) of the Securities Act. ☐

The Registrant hereby amends this Registration Statement on such date or dates as may be necessary to delay its effective date until the Registrant shall file a further amendment which specifically states that this Registration Statement shall thereafter become effective in accordance with Section 8(a) of the Securities Act of 1933, as amended, or until the Registration Statement shall become effective on such date as the Securities and Exchange Commission, acting pursuant to said Section 8(a), may determine.

EXPLANATORY NOTE

RF Acquisition Corp III is filing this Amendment No. 4 to its Registration Statement (this “Amendment) on Form S-1 (File No. 333-290947) (the “Registration Statement”) as an exhibit-only filing to file Exhibit 23.3 as indicated in Part II of this Amendment. Accordingly, this Amendment consists only of the facing page, this explanatory note, Part II of the Registration Statement, the signature pages to the Registration Statement, and the filed Exhibit 23.3. The prospectus constituting Part I of the Registration Statement has been omitted. 

PART II

INFORMATION NOT REQUIRED IN PROSPECTUS

Item 13. Other Expenses of Issuance and Distribution.

The estimated expenses payable by us in connection with the offering described in this registration statement (other than the underwriting discounts and commissions) will be as follows:

Item 14. Indemnification of Directors and Officers.

Cayman Islands law does not limit the extent to which a company’s memorandum and articles of association may provide for indemnification of officers and directors, except to the extent any such provision may be held by the Cayman Islands courts to be contrary to public policy, such as to provide indemnification against willful default, willful neglect, civil fraud or the consequences of committing a crime. Our amended and restated memorandum and articles of association will provide for indemnification of our officers and directors to the maximum extent permitted by law, including for any liability incurred in their capacities as such, except through their own actual fraud, willful default or willful neglect. We expect to purchase a policy of directors’ and officers’ liability insurance that insures our officers and directors against the cost of defense, settlement or payment of a judgment in some circumstances and insures us against our obligations to indemnify our officers and directors.

Our officers and directors have agreed to waive any right, title, interest or claim of any kind in or to any monies in the trust account, and have agreed to waive any right, title, interest or claim of any kind they may have in the future as a result of, or arising out of, any services provided to us and will not seek recourse against the trust account for any reason whatsoever (except to the extent they are entitled to funds from the trust account due to their ownership of public shares). Accordingly, any indemnification provided will only be able to be satisfied by us if (i) we have sufficient funds outside of the trust account or (ii) we consummate an initial business combination.

We believe that these provisions, the insurance and the indemnity agreements are necessary to attract and retain talented and experienced officers and directors.

Insofar as indemnification for liabilities arising under the Securities Act may be permitted to directors, officers or persons controlling us pursuant to the foregoing provisions, we have been informed that in the opinion of the SEC such indemnification is against public policy as expressed in the Securities Act and is therefore unenforceable.

We will enter into indemnity agreements with each of our officers and directors to provide contractual indemnification in addition to the indemnification provided for in our amended and restated memorandum and articles of association, a form of which is to be filed as an exhibit to this Registration Statement. These agreements will require us to indemnify these individuals to the fullest extent permitted under Cayman Islands law and to advance expenses incurred as a result of any proceeding against them as to which they could be indemnified.

Pursuant to the Underwriting Agreement to be filed as Exhibit 1.1 to this Registration Statement, we have agreed to indemnify the underwriters and the underwriters have agreed to indemnify us against certain civil liabilities that may be incurred in connection with this offering, including certain liabilities under the Securities Act.

Item 15. Recent Sales of Unregistered Securities.

On September 30, 2025, Alfa 30 Limited, our Sponsor, acquired an aggregate of 3,833,333 ordinary shares (“founder shares”) in exchange for a total capital contribution of $25,000 (or $0.0065 per share). Up to 500,000 founder shares are subject to forfeiture if the underwriters’ over-allotment is not exercised in full or in part. On October 9, 2025 we also entered into a subscription agreement to issue to EarlyBirdCapital, Inc. and its designees an aggregate of 250,000 ordinary shares for an aggregate purchase price of approximately $1,630, or approximately $0.0065 per share. Such securities were issued pursuant to the exemption from registration contained in Section 4(a)(2) of the Securities Act.

Additionally, our initial shareholders, including the Sponsor, and EBC have agreed that they and/or their designees will purchase an aggregate of 350,000 Private Placement Units (250,000 Private Placement Units to be purchased by the Sponsor and 100,000 Private Placement Units to be purchased by EBC and its designees). Additionally, our initial shareholders, including the Sponsor, and EBC have agreed that if the over-allotment option is exercised by the underwriters in full or in part, they and/or their designees will purchase from the Company up to an additional 30,000 Private Placement Units at a price of $10.00 per unit in an amount that is necessary to maintain in the Trust Account $10.00 per unit sold to the public in this offering. These purchases will take place on a private placement basis simultaneously this offering. The issuance will be made pursuant to the exemption from registration contained in Section 4(a)(2) of the Securities Act.

No underwriting discounts or commissions were paid with respect to such sales.

Item 16. Exhibits and Financial Statement Schedules.

Item 17. Undertakings.

EXHIBIT INDEX

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, as amended, the registrant has duly caused this Registration Statement on Form S-1 to be signed on its behalf by the undersigned, thereunto duly authorized, in the Cayman Islands, on the 29th day of January, 2026.

Pursuant to the requirements of the Securities Act of 1933, as amended, this Registration Statement has been signed below by the following persons in the capacities and on the dates indicated.

AUTHORIZED REPRESENTATIVE

Pursuant to the requirements of Section 6(a) of the Securities Act of 1933, the undersigned has signed this registration statement, solely in its capacity as the duly authorized representative of RF Acquisition Corp III, in Houston, Texas, on the 29th day of January, 2026.