In what way can I populate that field thru the application? I dont see that field in the mapping, I already checked for that. I'm looking to add the 'R' to my upload file. Do you mean to do a SQL update?
In the application the field is not shown. You could look via OMW to see if the field is hidden an make it visible. However this is considered a modification.
Otherwise a simple Update SQL statement is in order.