Rick's point is correct, though. The larger target isn't necessary for the recommended setup, 25x focal length. At that distance, the focus target of the LensAlign will be exactly the same size, regardless on focal length. It is fine to cover the center AF point, which is all you need.

The large target is used when you want to calibrate at a longer distance, to simulate how you use the lens (if that's how you use the lens, that is).