I would start out slowly at first and just pick up one foot and then drop it again keep doing that but hold for a few seconds longer each time . Work each foot in the same manner. If the problem is that she won't lift her foot, just keep tapping it's foot by its fetlock until he moves his foot . It could take a few days of this off and on and then it should get easier. Also when they do give you thier foot praise the heck out of them. Or give a treat if you like. I do both one day a treat the other day just praise. That way they don't get used to having a treat all the time.