How can I make one of the radio button required?

I tried to miss around the two radion buttons to make one of them required, but I felt I am not following the best pracrices.

https://preview.webflow.com/preview/reken-kunde-3f339c?utm_medium=preview_link&utm_source=designer&utm_content=reken-kunde-3f339c&preview=6ea2958c212dfb30c3bb193668af7d76&pageId=644edfdfdfe3492f999c2239&workflow=preview