Thank you, Rob, for your comment.

So, initially, I added the MHD module through the text command "Define/models/addon-module", and then saved my Fluent case. In Rocky, I loaded the Fluent case, and after that, everything is automated. I checked the Rocky setup, and it seems that it recognized the MHD field as attached below. However, I'm not using any MHD fields in particle motion. As a first step, I just wanted to check the coupling between Rocky and Fluent with MHD fields.