when I apply track matte key on my clip it becomes smaller

[DFreshVids]

Hi guys!

Trying use a track matte for a transition. I see that when I apply the track matte key the clip scales down and becomes smaller. How do I work around this please. Thanks

[Jim Curtis]

Track Matte isn't a transition effect. 

But, you seem to have stumbled onto my major criticism with Track Matte Key in Pr:  The matte will scale with the layer being matted.  The workaround is often to use Ae.  You could try Set Matte instead, but that shares the same issue.  Nesting your matte layer may help, too.  Depends.

Try providing more info, and maybe there's a solution for you without leaving Pr.