Yes that is what the shims are there for. Centring the RK is important, but at least it should be central enough that the saw cut clears it on both sides.
A way to check and to measure the centring is to slide a slip of wood along the RK from the back, and let the blade cut a cm or so. Then repeat on the other side of the RK and the other side of the slip. The two steps should be the same thickness, and if one side doesn't have a step at all, the RK needs moving.
Take obvious precautions by using push sticks, and using a long enough piece of wood that your pushing hand is well clear. Push the word against the RK but not so hard as to deflect it.
Keith