I would go over it again with the rotavator and pick off any persistent roots like couch from the surface. They are easier to see once they start to sprout, but at that stage have not taken root. I've never used weed killer. I find that many weeds just don't matter; the worst are couch grass, bindweed, creeping thistle, but horsetail is so fine it really isn't a problem, and bitter cress is tasty.