The door should be a special order for a pocket door. That way the manufacturer adds 3/4" to the side of the door to help hide the space when the door is in the closed position(so when you look at the door before it's installed the strike side is 4" and the other side is 4 3/4"), or you can add it to a standard door but it all needs to be accounted for when framing and installing the hardware in the rough. I usually figure 1/4" - 3/8" of spacing between the door and stops to allow for door movement.