He's already has signed it. In his will, he states, it should be mailed.

Kerry Asked To Sign Form Releasing All Naval Service Records
Judicial Watch Original Article

Judicial Watch, the public interest group that investigates and prosecutes government corruption, today asked Sen. John F. Kerry to keep his word to the American public and sign a Standard Form 180 (SF 180), “Request Pertaining to Military Records.” On Sunday, Jan. 30, 2005, during an appearance on the NBC News show “Meet the Press,” moderator Tim Russert asked Sen. Kerry (three times) if he would sign an SF 180 and release all of his military records.