Hi @pjain-6,
Not sure about rbInfo approach, but I did similar kind of customization way back (and still using it) of reading values from .properties file and getting them in drop down for IBA on WTDocument create layout.
If you wanna explore this approach, you can try instructions mentioned in KB article.
https://www.ptc.com/en/support/article?n=CS138327
Refer Below screen capture from my implementation:

I read somewhere, we can also extend this approach so that, if values are added or removed, modified list gets displayed in the drop-down, that too without restarting Windchill Method Server. 
I am trying to explore this approach, but no luck for now.. I will surely post my findings here if I found anything.
Regards,
Shirish