An additional encoding method for RSA signatures is proposed for inclusion in the IEEE P1363a document. Derived from the signature format in PKCS #1 v1.5, the encoding method has the advantages that it is relatively widely deployed and that it is more flexible in terms of hash function support compared to EMSA2, the method presently in IEEE P1363. The proposed encoding method shares many of the same security attributes as EMSA2, and is equally straightforward to implement.