Performance rating provide manager need to be Rejected by Employee

Summary

Performance rating provide manager need to be Rejected by Employee

Content

Employee should be presented with option to "Reject" or "Accept" the manager rating provided. I have configured "worker final feedback" as the last task in the process flow, I am not able to  add Accept/Reject drop down as DFF , also when the manager rating is rejected by employee, email need to be triggered for line manager manager for conflict resolution and settlement.

Kindly suggest a simpler solution  for the above  requirement.