First, start with a group. This could be for your existing small group or you can create a new group just for this RSVP event.
The RSVP Invite button allows you to populate a group with people you want to invite. Then click RSVP invite to invite them with an email or text that includes a link to accept or decline the invitation. It uses the same functionality as the Volunteer Schedule feature, but we changed the wording to make this new purpose clearer.