Bill4Time currently does not have a specific field to track referral sources - however, there is a way to do this so that your firm may report on this type of information:
Go to the desired Client or Matter profile.
Click into the Notes sub-tab, then click the blue "Add Note" button in order to record the referral source accordingly.
Go to Reports in your top navigation bar, then click into the Entry & User section of reports.
Select the Client Matter Entries report and in the report filters, make sure to check the box next to either "Show Client"/"Note Entries" or "Show Matter"/"Note Entries" (depending on where the referral note was recorded).
Click "Run Report".
Export the report into Excel by clicking the small gray icon in the top right corner of the report.
Sort through the notes according to "Entry Details/Description."