This is how it can be done in PD13, I expect PD12 will be similar. There are two methods:-
1) Select the clip and you will see a blue circle in the centre in the preview window. Move the cursor over the circle and it will change to two curved arrows. Left click and drag to rotate the frame.
If this doesn't give precise enough control:-
2) Select the clip and click on Power Tools. Check the box for Video Rotation and use the controls to rotate in 1 degree increments.
After rotation you may want to resize the clip slightly to remove black triangles at the corners. This is done by dragging the small white circles around the edge of the preview window.
Regards,
Mike
Home-build system:
Intel Core i5 Quad Core 3.3GHz, 2 x 4GB DDR3 1333MHz,
Asus Nvidia GT440 1GB, 2 x Western Digital WD10EARS 1TB, 1 x Seagate ST1000DM010 1TB,
Windows 7 Prof 64-bit, PD 9 Ultra 64, PD 13 Ultimate 64