The therapist would need to be comfortable treating transgender people and able to write the required letters to the other doctor. Not all therapist are skilled in this area so selection of the wrong one would be a waste of time and money. In some areas, school district have therapist they can call on but that may not be true where you live. It's also possible there is a therapist that could work with you over Skype but in order to get a medical referral, the therapist may need to live in your state. Again, if you have insurance, your choice of therapist may be limited by the plan that you have.