Drip edge on a "shed" style roof - high end of standalone single roof

The stores stock (or can order) a formed piece that is usually used as an outside corner that would work in your application. You'd lay the roofing down first and then apply the outside corner over the top and it would cover the top 4" of roofing and go down over the fascia 4". (You'd just be installing an outside corner piece horizontally instead of vertically...)

If I'm understanding your question correctly, when using metal roofing on a monoslope structure, to cap out the edge on the upper end of the roofing (the peak or "ridge" area), you would use a monoslope ridge cap. This can be special ordered through the Commercial Services Desk.