Add an event session that guests can RSVP to.
In the card editor, click the RSVP tab, then click + Add Itinerary.
Fill in Event Label, Event Date, Start Time and End Time. Choose the Guest Side this session is for.
Set the RSVP Before date, the Overall Attendance Limit and the Attendance Limit Per Guest. Tick Unlimited under a limit to remove it.
Click Save Draft or Publish. Guests see the RSVP button on your card when RSVP under Active Functions in the Cover tab is ticked.