You don't want the flint to lay against the frizzen. The paper match thickness is a good rule of thumb. And yes the sharper the flint, the more spark it will produce. When I was shooting my flinter the other day it was doing fine until the flint got dull. Then the troubles started. I have no skills in knapping a flint. Perhaps Roundball will see this post and give some detailed instructions on flint knapping to us all.