once you become aware that you are dreaming, you should have control of your actions … so rubbing your hands is simple. If you are a disembodied observer then commands would work best.
FILD (previously known as HILD): Finger Induced Lucid Dream (in Pathways to Lucidity)
MILD/WILD related, instead of focusing on HI, move your fingers while getting back to sleep. link to topic and part 2 and the current part
Good luck 