You can start a meeting with the number of contacts limited. Determine a four-digit meeting code, and share it with contacts with whom you want to have the meeting.
From the contacts list, click the contact to whom you want to connect.
Click [As Private].
Enter the meeting code, and click [Connect].
You cannot limit the number of contacts during the meeting.
To be able to join a meeting with the number of contacts limited after it has started, you must obtain the meeting code before it starts.