When billing for CPT codes 96138 and 96139 Neuropsychological testing by Technician, (1st 30 min and each additional 30) Who is the billing provider?

there is a post doctorate fellow performing as the technician, and the supervising PhD will be completing the reports, etc. I assume it is billed under the supervising? I have never used these codes and this is a new service we will be thinking of doing.

anyone have experience with this?

Thanks!