Request Rejection reason

Hi,

I am using the write off workflow WS21000102, Everything is working, however, when the approver rejects a write off only a vague description is sent to the initiator. I need to have the approver give a reason for the rejection. I cannot seem to find a way to have a screen pop up after the rejection asking for a reason (Likely filling one of the comments fields).

Any help would be appreciated

Thanks,