(1) Ask whoever gave you the referral if they know anyone. Chances are good that they may.
(2) Call Planned Parenthood. Some locations offer HRT for both FTMs and MTFs. You would have to check with each individual location though, unless you can find information for the specific locations on the internet.
(3) Call endocrinologists in your area. I'll post what to say on the phone below.
(4) If no endos are able/willing, check with general practitioners.
(5) Look for LGBTQ resources for your area. You may have to settle for something at a state level if there's nothing locally. But look for support or activist groups. Usually they either know what resources are available, or have members that may be willing to speak to you about who they go to.
On the phone: "Hi, I recently received a referral from a therapist to begin pursuing transgender hormone replacement therapy and I'm looking for a doctor to prescribe and monitor this. Is that something the doctor at your practice does? Could you find out for me?"
Chances are they will not know immediately and will need to call you back. I would look into Planned Parenthood and any LGBTQ resources you find first before moving on to the general population.