If you're using parchment paper on your tortilla press, but the dough is still sticking, you'll need to add more flour. Add a little bit at a time until the dough holds together, and doesn't stick to your fingers. Over time you'll learn what this feels like. I've heard from a few people who try to make the Cassava flour (grain free) tortillas below that it takes a LOT more cassava flour than the recipe calls for. And that's because each brand makes their flour a bit differently. Some are finer, and some are more coarse. It's best to go by weight when measuring flours.