True, and since most portraits fall in that category, it's a very simple process:
Originally Posted by MattKing
Turn on main light, point the dome at it and take a reading. Turn off main light.
Turn on fill light, point the dome at it and take a reading.
For a 2:1 ratio, fill should meter one stop less light than main.
Turn main light back on. point the dome at the camera, and take a reading.
Set the camera and take a picture.
More complex lighting setups will call for more complex metering procedures, hence the need for the flat panel.