3D Compositing with Action > Action: Surfaces >
Editing Tracker Offsets of a Bilinear Surface

Enable the Edit Offsets button to change the way the image is applied to a bilinear surface. For example, when you enable this button, an offset point appears for each of the surface's four corners (if Media Front is selected in the View box), then you use the Offsets controls to edit the offsets to match the corners of your square. View the result by disabling Edit Offsets.

You can then apply stabilizing data to a surface or surface offsets. See Four-Point Tracking.