If you have applications that you want to use within SURFCAM, edit the SURFCAM.INI file in the Surfnnnn folder.
By default UserApplications=0. The menu above is the result of editing as shown below.
If you do not provide a name, the default name of User App will be used.
You must save the SURFCAM.INI file and re-open SURFCAM for the change to appear.