A supervisor introducing their people works, but giving people the chance to introduce themselves sends a signal from the outset that they're invited to speak at the meeting. Usually that's my preference, but it depends on the meeting.

A good example of when I think a supervisor should introduce everyone is a meeting where a team lead is presenting a plan to a director that doesn't know everyone - the team lead introduces their people, and does the majority of the speaking, but can turn to a technician or an area subject expert to field a specific question that comes up.

To me generally, my people are at a meeting because their input is valued. I want them to speak for themselves, and that begins with them introducing themselves. If you're there to observe I'll introduce you, otherwise I want them to know they're there to listen AND speak.