Hey,
I've just downloadet the Rapido database, and was surprised not to find a .bak file inside the zip-package. Instead it contains a .bacpac, and renaming it to .bak doesn't do anything good either.
What's the idead of this .bacpac file? According to the manual, it should be a .bak file:
http://doc.dynamicweb.com/get-started/introduction/installation/installing-rapido
BR
Martin