Use the Maule tester. The Kitfox may fit in your Ultralight catagory but it a 100mph plus aircraft and should be tested using the Maule tester.
If you put a hole in the fabric accidently it sounds like your fabric is not acceptable for flight. Do not take a chance. If the fabric starts to peel you have no chance for survival. This is a video of the fabric on my airplane before recover. It peeled easily. Fabric that is good can not be ripped like this.
https://www.youtube.com/watch?v=Z5eXg-Ou1L4
Good luck
Fly safe.