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.