The word to describe the side of a face is YokoGao [横顔].
Yoko [横] is "side."
Kao [顔] is "face."
The "K" in "Kao" is softened to a "G" and thus YokoGao and not YokoKao.
In this case you can say...
"Rui-chan wa kawaii YokoGao shiteimasu ne" [るいちゃんはかわいいな横顔していますね] meaning "Rui has a cute YokoGao."
