Thank you for your post.
The .USR file is the actual database file. If you double click the application name, it will open using the .USR file. With the solutions I created, if I perform a Get Info on the file, the .USR files are set to open with Runtime. However, if I try to open this file without Runtime launched, I receive an error message. Instead, open the file using the Runtime application created. For example, when I create a Runtime from the file Test.fp7, I may name the Runtime application "TSGal", and inside the resulting "TSGal" folder, I will have the application TSGal and Test.USR (along with an Extensions folder and FMP Acknowledgements.pdf file).
Let me know if you need additional clarification.