what should i have called

[clips2]

runner on third, leading off the bag.1 foot outside foul territoryand other in fair territory. batter hits a ball that hits him..when it hit him it was going to be a foul ball. But, since he had part of his body in fair territory is he out.. i called foul ball and runner still on third...if a runner is hit by a ball in foul territory he is not out..but what happens when some part is in fair territory,,,,thanks for the help