If you could be persuaded to stay at your job, use this open-ended resignation letter to hint at a raise (but don't expect it to work every time!)
November 17, 2014
Dear Mr./Ms. Bossname,
It is with a measure of sadness that I tender my resignation, effective (date).
This has been a difficult choice, but at this point in my career, I feel that I need to make decisions that will move me forward into a supervisorial role as well as increase my income to a level that is commiserate with my skills and experience.
I have greatly enjoying working at (company), and I only wish my career trajectory could have continued here.