Be aware that this tool depends on goodwill and cooperation between the members of the team - no attempt has been made to guard against any ill-willed user who refuses to use the tool properly. It is quite easy to mis-use this tool if you are so inclined. As a result, this tool will probably be most useful in small teams where there is full mutual trust between the team members.
The tool is very simple: each time a properly set-up document is opened, a dialog appears where you can fill in or modify a 'tracker ID' - in most cases you'll simply use your first name or full name. The tool then appends the tracker ID (whatever it was) together with a time stamp at the end of a text box that sits on your pasteboard (by putting it on the pasteboard we can make sure it is not normally printed with the rest of the document. Of course, if you want to print it you would put it somewhere inside of the page). Over time, this text box accumulates a history of who opened the document, and when.
This tool is also NOT meant to be used for time tracking - it simply keeps track of who opened the document, and when - not for how long the document was edited.