Using both feet is essential to becoming a quality player. As a youth coach, you should make a point to run practice drills that force your players to use both feet. When you scrimmage, try playing weak foot only, where right footers must use their left, and left footers must use their right.  An easy stipulation to force your players to confront the issue. Here is a drill that is easy to mimmick at your next practice, courtesy of Martin Bidzinski and Reedswain.