Updating this since I know a lot of people googling Forensic Psychiatry Board studying end up on SDN.
I passed with a very comfortable margin. Overall, I felt it was a fair test. I walked out fairly certain that I'd passed without a problem. A handful of questions were out of left field but most questions were things I came across while studying. I definitely overstudied for this exam; I could've spent a quarter of the time studying and still passed without an issue.
Highest yield resources are the Landmark Case book mentioned in this thread along with the board review course. I actually though the board review course was lower yield than the Landmark Cases book. You could just stick to the Charles Scott lectures in the review course and be fine. I knew the landmark cases cold, made an Anki deck to help memorize them (happy to DM the deck to anyone who wants it). If you stuck with just those two resources, you'd have no problem passing with a comfortable margin.
The APA Forensic Psychiatry textbook is a good third resource to use if you want to read a textbook. I read it cover to cover and there were a handful of questions that I got right only because of that. I actually didn't find the Rosner and Scott textbook that helpful but to be fair, I only skimmed that because it was a lot more boring to read. I know there's an "Essential Board Review" book by Helen Farrell but the reviews on Amazon said it was basically just the review course notes that were condensed a bit so I didn't bother getting it.
Hope this helps future forensic psychiatry board takers.