Ah I understand now. I think the issue is that the Image element is sibling to the Ellipse and Path elements that make up the actual button itself. I don't think there really is a good way to set this up and still allow someone to have an image that is outside the approximately 24x24 square that could fit inside the circle.

Actually... I didn't want to change the size of the button.  I just wanted the image that I am using toi "fit" inside the button.  It doesn't seem to matter how small I make the image file.  When it gets overlayed onto the button it is bigger than the button.  The sample that is displayed in your documentation shows a "star" image overlayed onto the button and the star fits inside the button.  That is what I wanted my image to do also.

By playing around with my image file (gif with a transparent background) I was able to get it to "appear" to fit inside the button.  It would have been nice to just be able to tell the control to "size to fit" the image to the button or something like that.

The size of the application menu button is fixed in the XamRibbon's template to honor the required visual guidelines outlined in the Office UI Design Guidelines.

lol I was just about to ask the same question.

 Hopefully someone responds who knows. Tried different properties but could not seem to find. Last option would be to manual adjust the control template.

So how do you change the size of the image on the application button?  I have adjusted the actual size of the image I am using, but, it keeps getting "resized" at runtime when it overlays the button.

Thanks,