Provide depth information for cut in drawing

[nedlane]

Hey everybody, I am new to this software so I am sure this is possible and I am just doing it wrong, but I was wondering how to add in a line to indicate during manufacturing how deep to cut a hole.
For example see this drawing below where I would like to indicate the cut depth to be 15mm as overlaid using crude screenshot tools

Regards,
Ned

[keksboy]

You can doubleclick on one View, and there should be an Button under the view where you can toggle the visibility of inside geometrie