Since kiridashi are generally marking knives for joinery, you want the bevel to be on the outside of whichever hand is going to be used, that way the flat is on the inside. This makes it so you can get a perfect cut along a straight edge without the bevel trying to push the cut away from the straight edge. This means that, when held in the hand, a right-handed kiridashi has the bevel on the right, and a left-handed kiridashi has the bevel on the left.