I have yet to find any configuration or basic discussion on this topic. We have the Improvements / Incident reporting add-on. Looking for similar capabilities for the RISK add-on, allowing us to create additional fields required by our Risk team.
Doesn't appear this is possible from my research and review of Risk configurations as a Promaster.
Its not possible to customise the Risk form in the same manor as we can do the Improvements. If this is functionality that I would like to see, then you can post this as an idea on our User Voice page (https://nintex.uservoice.com/).