You could simply for every frame you get check the time and only draw a new frame when the right amount of time has passed. Though I don't think there is much point in using
requestAnimationFrame when you are updating that slowly.
And for the record 3 fps is very slow. If you are doing so few sprites it might be better to not talk about fps, and instead talk about time between the individual frames, and then also realize that there doesn't have to be an equal amount of time between frames in any given animation. You can adjust the time that every individual frame is shown depending on what looks good, and if there is a visible glitch you can add in an extra frame right at that moment without having to change the rest of the animation.