That's the part I thought your talking about. This is a chuck of plastic/rubber piece that goes over the pinch weld. AMES calls it "MOLDED DR JAMB EDGE". However,it would leave some of the metal showing between the vinyl panel and the JAMB EDGE.

So I think you need both. Put the vinyl material on first, then the vinyl door panel, and then the JAMB EDGE.

Look at the blue area. That will show the sheet metal if you don't put that vinyl piece on.

NOTE: You must consider the JAMB edge butts up against front door panel when you close the door. Some of you might notice there doors will be harder to close.