Import the ".xml" file.

Select a specific clip in the timeline or double-click on the frame you want to edit.

Go over to the Video tab on the top right side of the screen. This will give you a whole slew of resizing options for your footage. In this menu is a drop-down menu labeled cropping.

Here, you'll have options to Crop Left, Crop Right, Crop Top, and Crop Bottom. Changing these values will crop the bottom and the sides of the video.