Right-click on an object that is part of the DWF underlay.
Click DWF Clip.
At the command prompt, enter n (New
Boundary).
Enter p (Polygonal) or r (Rectangular), and then draw the boundary on the
underlay.
If you are
drawing a polygonal boundary, you are prompted to specify
consecutive vertices. To finish drawing a polygon, press ENTER or
right-click anywhere in the drawing area.
Shortcut menu: Right-click a DWF
underlay object. Click DWF Clip.