Creating hold tabs

I have created an STL in Shapr3D and need to add hold tabs in preparation for CNC. Is there a way to do this?

https://support.shapr3d.com/hc/en-us/requests/new

Just create a sketch on the side of the object where you want each tab to be and extrude.

But won’t that be seen as a protrusion to mill out since it has an end surface to it??