Run AppleScript when files are added to folder/subfolder?

I am brand new to Hazel, and I'm hoping someone here can help me set up a rule I've been trying to make. I'd like to have AppleScript run every time a file is added to a specific folder (or any of its subfolders). In case it matters, the folder is where all my ebooks are stored, and the AppleScript syncs the ebooks to my reading device. I have already automated the process of getting the epub files into the folder, and I'm just trying to automate this very last step of syncing them to my device. There isn't an easy way of doing this, but I created a Keyboard Maestro macro that can do it. I just need to trigger this macro (via AppleScript) any time a new book is added to the folder. I'd really appreciate any guidance on getting this working.

What rule do you have so far and where are you running into trouble?