I recently worked with Dawn and Eric at PeopleClick to better understand its candidate source tracking capability and how to implement it for clients. The good news is that it's automated in almost all cases, except when the client has added some custom fields for the purposes of tracking candidate source.
If you have any questions about how it works, please let me know and I can share examples or connect you with the right people there for implementation advice.
I have updated ATS Report Card accordingly to reflect the correct information for PeopleClick; I also added CATS and Sendouts as part of the update.
