Selecting this option will open the Add Parts window. This window has several options, you can select default folders rcim_work, or Router-CIM as well as set the default types of files to DWG, DXF, or SCN files. You can see a preview of the part, unless multiple parts are selected.
To scale your parts from inch to metric or metric to inch prior to processing the job, please go to 'Scale Part Geometry in Router-CIM Automation Suite'.