How to process application assets files when creating .dmg on Mac OS X

We've just finished development of our application and are trying to create a .dmg disk image for public distribution. The applicaiton is developed with Qt 4.8.3 (binary framework installation) on Mac OS X. We've successfully used macdeployqt tool to create the application bundle along with a .dmg disk image file. The macdeployqt is magic and help copying Qt and 3rd party libraries into AppName.app/Contents/Frameworks directory. We can run the app from inside the bundle directory (AppName.app/Contents/MacOS) from either terminal ($ ./appname) or Finder (double mouse click).
However, after we installed the application using the .dmg file and run our app from the Launchpad, our app crashed at startup and the debug information indicates that the crash reason is that the assets files could not be loaded. Our app depends on quite a number of assets files (fonts, map data, palette data, help documents etc.) to run. We just copy these assets files into AppName.app/Contents/MacOS directory (where the executable file 'appname' resides) when we create the .dmg file as in our code these asset files are referenced in relative path.
So how to figure this issue out? Thanks in advance.