Hi there.
I was stuck with this one for quite some time and found the following solutions:
1- You can set the scalable attribute to false, and have the units of the drawing methods behave like absolute pixel units.
2- If you need the shape to scale, you can export the profile checking the Element Size checkbox. If you do this, the elements will be sized after the size of the stereotypes on the profile diagram.
The only problem is that, if you use this second approach, there's usually a limit to how small you can scale the stereotype element... to circumvent this, you need to go to the diagram properties and uncheck all element feature visibility checkboxes, or you need to change the auto-size behavior of the elements.
Either way, you'll be able to resize your stereotypes and, when you drop the elements from the toolbar, they will have the same size they had when you defined the profile.
There was a third option, setting the width and the height on the stereotype attributes, but I don't remember what were the attribute names.
Hope this helps.
Marcelo