I agree with Walker, this is a bad practice. Think of your physician's malpractice carrier, how would they feel because if anything goes wrong it will come back on the physician's malpractice because according to the claim, the physician was there!
An RN is not the same as an NP. The most that an RN can bill would be 99211 - if the doctor was present in the office suite. Per CPT this type of presenting problem "may not require the presence of a physician."
Incident to billing requires that an qualified Allied Health Professional (such as an NP or PA) perform the service as a follow-up to an already established treatment plan. That's a different thing and the level of service may be higher than 99211.