One way is to cut a strip about 3/8 or 1/2 inch wide, then crease it between your fingers so that you can iron the crease into the joint between the fin and the deck (you may need to make several cuts perpendicular to the crease, but preserving a thin band). This creates a base for the next step. Then cut the deck covering piece as closely as you can to fit neatly around the fin and iron the edge into the corner. Done well, the seam will not be noticeable. A trim iron is useful, to say the least. Good luck, Dzl