Apple Final Cut Pro 7 - Manual (Page 70)

70 Chapter 3 Preparing Clips in the Viewer
Move the playhead ahead in the Viewer to the frame where you want the change 3
to end. In this case, place the playhead at the approximate position you see in the
illustration below. This will be the frame at which the clip is completely resized.
Move the playhead
to approximately
this position.
Click the Add Motion Keyframe button to set another keyframe. 4
Resize and reposition the clip to fill the normal display area. 5
Play the clip in the Viewer to see it change size over time. 6