Some Epsom salt (magnesium sulfate) in a hot bath is one way to get some magnesium. The magnesium will absorb through the skin. Magnesium is supposed to be relaxing so before bed is a good time to take it, either orally as a magnesium supplement (not Epsom salts) or as a bath soaking type supplement (Epsom salts).

I don't know if it would help with restless leg or not, but I have used it in our Juccuzi type bath tub many times for various sore muscles or injuries.