If you're running the new DWF Composer 2. You'll notice that there is a new button on your toolbar that looks like a camera. No its not a link to your Webcam. Its actually a Snap Shot tool. This tool once issued by the button will bring up a red rectangular window. This red rectangular snap shot tool allows you to maneuver this red rectangle over an area of your screen and take a snap shot of your screen. Once the snap shot is taken, it will export that snap shot to a page in your DWF. The snap shot can be any size you need. Once the snap shot is take it can be marked up right in DWF Composer. This red window can also be re-sized on any side, corner and moved around. The Snap shot tool also allows you to see the size of the image before you take your snap shot.
Here is the Snap Shot rectangle.
Here is the final result after your snap shot.