Yes ! Referral allows you to comments and messages for Referrals under yours ‘Track Referral’ section.

Comments are for recruiter’s internal use and NOT Visible to employees.

Messages to employees can be mentioned under the message section.

These can typically be the reasons/justifications for a status like whether the profile was relevant or why it got rejected.

Employees get the messages on their referral site as well as in the referral status mails.