Superman's appearances in Supergirl so far have been fleeting. As far as I can tell, his face hasn't been shown. The sun's behind him in the scene where he finds Supergirl the first time, and in episode 3 he's shown from Supergirl's (prone) view from behind.
Is it just to decrease his prominence? Or, are there (possibly contractual or licensing) conditions to his appearance in the show?
IMHO trying to not show his face seems rather clumsy - it heightens curiosity as to what he looks like, and thereby increases attention to Superman.