To invite another attendee to an appointment, open their user profile and click Schedule appointment. Note that the Appointments card on the profile is only available when that user has opted in for it.
When scheduling the appointment, click Add virtual room below the location.
After scheduling the appointment, the other person will receive a notification and can accept or decline the invite. You can access all your appointments through My Programme. Through the appointment details page in the side panel, you can enter the virtual room.
The virtual room is private to just the two users in the appointment. Both users can share their screen to present.