I do this the easy way. This photograph of my father, my younger brother, and me was taken
in the early 1940s. The print I have has smooth edges, but I wanted the deckled edges that
was used for early prints.
I found another photograph with deckled edges, scanned it on a black background, and
cut out the middle in a rectangle. This photo was placed in a layer below the cut-out
frame.
It would look better if I'd age that white border a bit and put some minor
creases in it.
Using this method, the frame can be kept as a .psd and other photos can
be inserted as layers without re-doing things.
Mod Edit: Added image