Document Publisher and Change Request case record

We are trying to create Word/PDF change request form populated with data in the fields from a Case record (change request). We can get base data correctly populated i.e. { !field=EnhancementRequest.SYSID } returns the reference number of the change request. We do however want to add information such as "createdby" but not quite sure what the correct relationship is. Has anyone done something similar and could give us a steer on the correct syntax for insertion in the comment?