searching rs.4chan.org

How do I form search queries in rs.4chan.org?

For instance, I want to search for "kg-foobar", but searching for kg-foobar yields results for only foobar (ignoring kg) and adding quotes makes it return nothing, even though if I search for other strings I can see that there are results containing the substring "kg-foobar".

It's not an essentially imageboard question.  There's no board particularly suited to answering it, but I figured I'd have the best odds here.