Hi. I'm working as a writer and helping with puzzles and art for a submission to this jam. I'm not the main developer, but I would like to be counted as having worked on this game.

I know some other jams allow you to form teams so you're all included on a game's submission page and can rate other entries. Is there a good way to do this with the RPG Maker Horror jam?

This isn't something jam specific, it's just that whomever makes the project page has to include you as a contributor. So ask them.