I a level balanced turn, there should be almost no requirement for rudder at all.
Rudder is only required when using the ailerons as this is when adverse aileron drag and the associated yaw is present.
You should not need to provide a continuous rudder input at all.
If any continuous input is required, as ProfChrisReed has mentioned, it may be the smallest (read very small) out of turn rudder, as most aircraft tend to want to roll into the turn you tend to stop this with a little out of turn aileron and as already mention any time you use aileron to balance a little rudder is required in that direstion also.
Sorry to get all technical but too many people leave a continuous input on the rudder in a turn putting the aircraft out of balance, and then proceed to wonder why, or just plain ignore it.