|User (Staff member?) Geekahedron added the wiki page on using the roller to produce FATE dice results.
Fate dice are 6 sided, with two negative sides [-1], two blank results [+0], and two positive results [+1]. You always roll 4 at a time, and count up the sides, with negative sides subtracting from the total, and positive ones adding to it. Your result will range from -4 to +4. In the official rules, you can't roll below a -2, but in practice on M-W, most people ignore that and go with whatever result you get, as low as -4.
The M-W syntax: [dice]4dF[/dice]
The capital F is required, because if it's not capitalized, the roll will produce all 1's. Also, [roll] and [dice] are interchangeable. I prefer [dice] so that I can use OOC tags to make them a seamless part of the narrative. You do what you want (or whatever your GM wants).