Testing WebAPI with Fiddler

I was wanting to test some WebAPI Methods via Fiddler so that I could all be working on one machine, debug, and make sure that everything is working.  Here is what my fiddler setup looks like:

 

We're calling into a method with the signature:

        public List Post([FromBody] UserLocation value)
        {
//............
        }
 

The UserLocation object has the following signature;

    public class UserLocation
    {
        public string AppKey { get; set; }
        public double Latitude { get; set; }
        public double Longitude { get; set; }
    }