Although this question is quite old, I had exactly the same question and could not find an answer. After some digging I found that you need to copy 3 files from this location (replace <username> with your account name):
/Users/<username>/Library/Containers/com.microsoft.rdc.macos/Data/Library/Application Support/com.microsoft.rdc.macos/
In this folder you need to copy the following files:
com.microsoft.rdc.application-data.sqlite
com.microsoft.rdc.application-data.sqlite-shm
com.microsoft.rdc.application-data.sqlite-wal
Apparently these files contain the definitions, the only thing which was not working were the saved credentials. (and that is a good thing imho :))
Maybe not needed for the original topic starter, but it might come in handy for someone else :)