Use
the Burn Letterbox tool in the Fx menu to burn a letterbox format
into a clip. You set the Letterbox options for the clip using the
Player Letterbox controls. When you select a clip with letterbox
formatting, Burn Letterbox detects the format.
To burn in letterbox:
Set the Letterbox options for the clip
in the Player.
With Fx selected from the A/V Tools box,
click Burn Letterbox.
Select the clip on which to apply the
letterbox format.
Select the destination in the Source
Area or Record Area for the letterbox clip.