Janet, all he had to do was make the piece,present it to the assay office and tell them what he wanted them to put to identify him. Usually his initials.
Dave
Perhaps more sensible would be that he put his own id on the piece then gave it to the assay office to add the other 2 components of the mark. That way he could decide where the full mark would go on his piece and his mark would be consistent from piece to piece. Either way the only qualification he needed to put his id on was that he or his employee made the piece
Dave