This is what makes the curst flaky. Also, do not mix the dough more than necessary. This will make it tough. If you do not have a food processor use a pastry cutter of a couple of knives to cut the butter into the flour. It may seem easier to do this with your hands, but the crust will not be as good.
Some people claim that using lard or rendered goose fat results in a better crust than butter.
It should hang over the edges. Use a knife to cut the dough even with the edge of the pie dish. Wrap the leftover dough in plastic wrap. Put the pie crust and the leftover dough back in the refrigerator. Whether you buy a crust or make your own, you are now ready for the filling.