To set an individual as time reviewer for another individual's time entries, you will need to go to the Time Reviewer's user profile, then to the Time Review Setup tab. On that tab, you will check the boxes of the users that this person needs to review.
A Time Reviewer must have access to a time entry's prospect or they will not be added as a time reviewer for those entries.
1. Click on Admin from the Menu bar
2. Click on Users