Guess what? I got rls again, while taking enough iron! The problem the 2nd time? I was on a low salt diet as my blood pressure was just a tad higher than the normal range. So, I upped by salt and took Celery seed to handle the blood pressure problem (see research on Celery seed and BP) and the rls went away again. Just fyi.
I learned any electrolyte imbalance can also cause rls, like not enough magnesium or calcium (the 2 have to be in balance) or postassium.