I just browsed through the manual (for the 40 size kit). It is not clear on what to do.

My gut response is that you should cut a slot in the rudder so that the metal rod can move freely, and the rudder slots over (bridges) the rod. The closes I can come to an answer is the picture on page 31 of the manual above step 12. See how there is a hollow in the rudder to lety the rod fit?

gus