Hello,
You can do it without RadAnimation, simply by use two Storyboards. One storyboard for scaling up and one for scaling down.
And on <Image> element you need to set RenderTransformOrigin="1,0" for image transformation to down/left direction. In storyboards you can set desired duration of animation and desired size after scale (attribute "To" in "FullSizeStoryboard" storyboard). Link to sample project:
http://www.speedyshare.com/files/29564174/ImageScale.zip.
Regards,
Michał Zalewski