The fold lines are on the obverse (back) sides.

Here are the instructions that come with the PE fret.

Here the PE appears to be attached to the radiator on the sprue. The edging appears to be .010 plastic rod used as a border.

Here is an up close image version of the previous image.

The following images are from real aircraft. The first is from a late model Fok. D.VII (Alb.) in the hands of the AEF post war.

Here are late production Fokker D.VII (OAW) type in their "Traveling clothes" awaiting disbursement at Romoratin post war.

An early production Fok. D.VII.

Of course the reasoning behind the use of adhesives other than "Cyano" is the time needed to reposition the PE part on the face of the radiator kit part. Also It is not a screen or mesh part as the Cyano might block up the screen and ruin the effect. PVA or another acrylic liquid is easy to blotter up on the edges.

Cool, I have ordered two sets for my D.VII kits.