Add Rectangle object to Adorner?

Hello all:

I'm using an Adorner to do some custom overlay rectangle drawing using the "drawingContext.DrawRectangle(...)" approach. I'd like to experiment with applying bitmap effects to these rectangles, but all the tutorials I've seen that are applicable are using the "Effect" property of "Shape" objects. How does one add a "Rectangle" object to the adorner (rather than using the "DrawRectangle" approach)? Or - alternatively - is it possible to apply an Effect to the rectangle drawn via the "DrawRectangle" function and, if so, how?

Thank you in advance.