You have the option to set your Referrers as broad or specific as needed based on your Center's needs. You may use the options set forth on the General Intake Form (GIF) or whatever options you'd like.
You may wish to track how many referrals you are receiving from Dr. X or Doula A, Birthing Center, etc. In that case set them as Referrers. If you just have a one-off, you may want to just use Medical Referral or Friend.
Note: In order to select a Referrer in the Referred By field on the New Client form you must first set-up your Referrers under Profile | Application Settings