Apple Shake 4 - Manual (Page 576)

576 Chapter 20 Rotoscoping
Button Usage Example
To easily animate the QuickShape, enable
Autokey and move the points. To enter a
new keyframe, move to a new time, and
change the shape’s position (or the control
points of the shape). In this example, the
shape is smaller on the second keyframe. As
you drag the playhead, the shape
interpolates between the two keyframes.
Delete a keyframe (if present) at the current
frame.