The HBOND sections of the PSF begin with lines containing the strings "!NDON: donors" and likewise "!NACC: acceptors", and are listed in pairs as donor,donor-antecedent or acceptor,acceptor-antecedent. It is, however, mostly irrelevant as the HBOND term of the potential isn't used except for analysis, and for that it is trivial to use the DONOR and ACCEPTOR commands to define them on the fly. You don't need a new PSF for that.

Rick Venable
computational chemist