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