The skin should be dimpled for the screw as well as the rivets. You only have one skin layer to rivet through. There is not enough material there to countersink.
Again no plans in front of me but I believe it calls for a K1100-08 nutplate which should be a dimpled nutplate (dimpled for the rivets only).
after looking all over the shop, I found the correct nut plates and figured out why I was confused.
Thanks
ken