if you read the directions it says to tape off where you dont want the coating to go. so tape off the painted area of the tail gate, i went to the edge with it, looked more complete. i also ran a tape line under the bed rail side, you cant see it but its better than the line being all over the place, and the front of the bed, where you can see the line.
also check to see if you have small 1/8 inch drain holes in the front of the bed, ( at the front in the bed lower rails) if so, after you paint them over, clear them with a tooth pick or something, so your bed bottom rails drain still. had this on my 03, no idea if fords do this, i also had the big holes in the front corners of the bed.