If the wings are level and the airmass isn't changing it's speed, then holding in rudder to maintain a ground track isn't right.

But on a typical crosswind landing we tend to need to lean on the rudder to get the plane to weathercock into the wind as it slows for the landing. The main difference between full size and RC is that windspeed is a much more significant component of our airspeed, so a 5kn crosswind is going to require a much larger change in yaw to maintain a groundtrack as the model slows down than for a full size.

That change in yaw has to be rudder induced because we all know planes don't weathercock into a crosswind as they slow down, they just change groundtrack.

Lowering the upwind wing (ie initiate a very gentle turn) will also help maintain the ground track as the airspeed drops for landing, but if you "must" keep wings level then rudder does the job.