How do you vouch for posts? I didn't know that was a feature, and I have 900 karma which should be enough, but it doesn't show up the next to the flag (https://

How do you vouch for posts? I didn't know that was a feature, and I have 900 karma which should be enough, but it doesn't show up the next to the flag (https://www.ycombinator.com/blog/two-hn-announcements/ https://www.ycombinator.com/blog/two-hn-announcements/). The flags make sense though, it's too explicitly political and has opinions many on the site don't like.