To rest rough a 2D Pocket, enable the “Rest Machining” check box on the geometry tab, and enter the tool diameter, tool corner radius and stock to leave settings that was used previously on the geometry.
So if, for example, you start roughing with a 20mm tool that does not fit in all areas of a given pocket, then make another 2D Pocket operation with a smaller tool, and specify 20mm for the “Rest Material Tool Diameter” parameter.
Enabling Rest Machining on a 2D Pocket operation
The resulting toolpaths:
2D Pocket with 20mm tool
2D Pocket with 10mm tool, and Rest Machining enabled