That ASRock press release clearly indicates it's a M-ATX motherboard. It may be a good motherboard, but you can't ignore CPU cooling requirements. A 65W Ryzen is more appropriate for SFF.
Thanks. I was searching around and there is a slight possibility I could squeeze this thing into what would still be categorized as a SFF machine, but it is highly unlikely. I also don't want to experiment with attempting such a feat. There is the Zotac EN1080K and this future Digital Storm offering, which both use Intel processors. https://www.anandtech.com/show/12232/digital-storm-announces-project-spark-micro-stx-platform-up-to-gtx-1080-and-i78700k-hardline-cooling