Requested Refund Amount- Viginia State Return Filing Status 4

How do I calculate my "Requested refund amount" for the following situation? I am filing my state return for Virginia using Filing Status 4 - Married, Filing a Separate Return. My spouse and I Arizona residents and are not/have never been residents of Virginia. Only I have wages from Virginia. TurboTax calculates my taxes owed for Virginia as $0. In TurboTax I chose the "employer mistakenly withheld" option for myself and the "non of the above" option for my spouse.  The next prompt is to "Your Requested Refund Amount"; how do I go about finding/calculating this amount?