How to import valid %ProgramFiles% folder into the registry

We have x86 and x64 systems and we need to import some key-values into the registry.

For example:

[HKEY_USERS\.Default\XFS\SERVICE_PROVIDERS\Device]
"dllname"="%ProgramFiles%\\Company\\MegaLib.dll"

The thing is that when we use %ProgramFiles%, it seems that the program which should handle the value is not able to read the path. When I change the value of the path to the absolute path everything goes well. What is the best way to import a correct path? Is there any way just to write the correct .reg file, or we should execute a little bit of custom code in order to determine the architecture of the current system and properly change the path inside the .reg file?