- Log in to your admin panel
- Navigate to Settings > Plans
- Choose an existing plan, or create a new one
- Scroll down to the section titled "Collect Extra Info from Members who Select this Plan"
- Click "Add Another Field" and select your field*
- In the Display Context area, choose whether the question should be asked when a member is signing up ("signup") or renewing ("renewal") this particular plan
- Save your plan
The custom question appears on the signup page: