Final answer:
The most appropriate nursing action for the RN to delegate to a dialysis technician is checking blood pressure before starting dialysis.
Step-by-step explanation:
The most appropriate nursing action for the registered nurse (RN) to delegate to a dialysis technician in this case is to check blood pressure before starting dialysis. Dialysis technicians typically work in direct patient care under the supervision of a registered nurse. Checking the patient's blood pressure is a routine task that can be safely delegated to a dialysis technician.