Rivet the clip to one end of the welt, then hook it in the center notch and pull it around to the other side and mark where to rivet the other hook in the center notch. Rivet the other end and install the welt, then use a scratch awl to poke holes for the two screws. When you run the screws in it will tighten the welt. I use the hooks in the center notches so I can adjust tighter or looser if need be.
This is the cowl to hood welt I thought you were referring to, but I see Bill and Mitch have answered your question.