It might be difficult, but if the doctor asked you to write it because he/she is too busy or something then do what they say. This is a great opportunity you have here. You have a blank slate and can make yourself seem incredible
Yes, make it a confirmation of shadowing. But you also need to include things about your character, interest in the profession, likeableness, friendliness, etc. Put yourself in the mind of the podiatrist and write from that point of view