So the big question is still how she'll get him to fall for her...
At least, I hope that'll happen at the end of this arc. I don't want Naoya to just accumulate one-sided love interests like in every other harem plot, which would make this story turn into "Saki reaction faces: the manga".
Given the way things moved with Nagisa, I expect that the next "step" for Rika is to become friends with Saki, or rather, get Saki to approve of her.