Attaching at this point may prove difficult to make look good. When I design a sheath with a frog, I typically attach the frog to the beltloop, and make it a seperate piece.Since there is no strength inlvolved in using the piece to display a concho, you might get away with with simply gluing it to the belt loop and putting in a couple of small tacks into the welt from the back.I have seen this done and it looked pretty good.Another trickI use is to notch the edge the thickness of the collar and wet form it around the main body,tis makes for a much slimmer look.Dave