During the checkin process have a section or even a "Custom Field" that enables you to add specific items that the customer is checking in with their computer. This list should be able to dynamically expand but just adding another line. Upon checking in the computer a label for each item in the "Articles for Check-in" area should print.

This way every item that a customer leaves with you can be labeled and tracked. For instance a laptop charger, USB dongle (mouse or wifi), bag or carrying case, external hard drive, etc.

Then if you implement a check out procedure in RS have a spot to record that each item was indeed given to the customer.