Clicking “Reply” doesn’t seem to actually quote the post. But I saw someone else do it so I know it’s possible. Can someone explain?
You can either press quote then the speech bubble to the left in the text editor
or press quote then somewhere other than the editor then Q
or highlight that which you want to quote then press Quote or Reply
aaaaand you just taught me the coolest way to quote, thanks!
That’s cool, thanks. Apparently this approach doesn’t work for nested quotes (as far as I can tell), but it’s great for the normal case.
So, does Rikai-chan have a problem with Discourse, because of quoting?
Rikaikun (Chrome) doesn’t have a problem with quoting.
When you want to do a nested quote, or quote an entire post (instead of just a sentence with the highlight method), first click Reply on the post you wish to quote, then click the speech bubble at the top of the reply, and that entire post will be quoted. As I’ve done here. : D
You can do it too! 
I’m using a Jisho.org bookmarklet myself instead of Rikai, and the Quote button can sometimes cover some of the element I’ve hilighted so I’m not always 100% sure I’ve picked the right thing until my Jisho pop-up appears. It’s slightly inconvenient when I want to do that, but it still works.
Mine is Safarikai on Safari, and there is usually a problem with the first character that cannot be hi-lighted, so I just use Right Click + Google search, instead.