Modifying search engines

I would like to use as a search engine. I have it listed in the “Manage search engines” window, and want to access it from the URL bar with a keyword. In other words, by typing in " random word, I would like to search for the phrase “random word.” I have set as the keyword, but when I try this, all i get is a search for this text via my default search engine.

How do I search for text within a particular site, like I want to do?