Already mentioned it before, when just saw first playthrough on youtube. It's the same as in P&P D&D, rolling openly and revealing results of perception check will only lead to metagaming. In P&P players will take notice they missed something, and will tediously will try to rediscover it. In CRPG that will simply lead to savescamming.
Solution is pretty much the same as in P&P rpg - passive perception.
10 + wis + PB (if proficient in perception). If it's high enough - it will automatically reveal secrets. If not - players should not know about check been made at all.
If player suspicious some part of dungeon (or otherwise) might contain a secret - he might attempt either active perception check, or investigation check. But even then game should not inform player on whenever check was failed, or there simply wasn't anything in there.
