How to set Height/Width for OvalGeometry/RectangleGeometry

[begleysm]

My initial implementation uses CircleGeometry's in a ScatterSeries like this

SeriesData =
            new ScatterSeries<ObservablePoint, CircleGeometry>
            {
                Values = myPoints,
                GeometrySize = 20,
            };

I want to switch to an OvalGeometry and control the Height & Width characteristics independently. I'm having trouble figuring out how to do this. Something like the below does NOT work as Height & Width aren't exposed as part of ScatterSeries as best I can tell.

SeriesData =
            new ScatterSeries<ObservablePoint, OvalGeometry>
            {
                Values = myPoints,
                Height = 10,
                Width = 20,
            };

Can anyone help me achieve what I'm going for? To use Ovals with a defined Height/Width as the Geometries for the ScatterSeries?