>Do not the answer, but maybe you can launch it manually when your application starts by running osk.exe (you could check if it is not already running)
>
>[Update]Check this link if it is of any help http://www.thewindowsclub.com/windows-onscreen-keyboard[/Update]

In my case it is not the same keyboard as the one that us default on my tablet. I do not know for the surface pro though.
I was hoping on something like a windows setting