A 2D Contour operation is used once again to create the required chamfers.
2D Milling panel
2D Contour
.
to open the Tool Library.
to close the Tool Library dialog. 
Because a chamfering tool was selected, Inventor CAM automatically enables the Chamfer group.
button, or right-click in the graphics window and select OK from the marking menu, to exit 2D Contour and create the toolpath. 
Continue to To Machine the Countersinks...