It has been a long time since I had been able to work on my Panther. The frame was assembled a couple of months ago and I decided it was time to get back at it. The first step in match drilling the skin to the ribs is to use rachet straps and wood blocks to bring the trqailing edge of the skin to match that of the aft spar. Be careful not to over tighten. It takes a bit of care to be sure the holes in the skin are centered on the rib centerlines. It is possible to reach under the frame to move the forward ribs if needed as the bottom skin is not clecoed yet. My advice: Follow the instructions in the manual and plans and it becomes very easy...just takes a bit of time.