If you have a "Where did you hear about us?" or Enquiry Source field on your Prospectus Requests form, then you can customise what appears in this field from the Prospectus Requests app.
To do this, go to the Settings Cog of Prospectus Requests. You will then see a tab for Enquiry Sources
To add a new source, click on the Add Source button in the top right of the screen, add the source and press save:
Voila! The Source will now appear in your Prospectus Requests form.