You want the kick-up rudder to kick up.  I wouldn't want to wait for the fit of the rudder blade between the cheeks to loosen up from use, if it even would.  The instructions for my Skerry were to reduce (by sanding) the thickness of the top part of the rudder blade sufficiently to get a nice slip fit, taking a little material off both sides so as to not sand through the veneer ply.  Obviously, when you are done, make sure the entire surface is sealed with epoxy.

   Just the advice I needed. Thanks !

I too sanded the rudder blade appropriately.  Also,when gluing the rudder cheeks onto the center portion (forget the name), I wedged the cheeks apart a bit wider that the rudder blade.  I actually put two wedges in - upper and lower.  Works fine.  Note:  with thickened epoxy, the cheeks and center filler do not need to fit perfectly flatly together.  Be sure to scoop out any glue from inside the rudder before it dries;