How precisely are Sanctioned Psykers designated?

In a game of Rogue Trader, I briefly contemplated (but ultimately rejected for unrelated reasons) taking a rank in Awakened Psyker, and I wondered if rather than trying to hide his talent, it might be safer to simply declare that of course he'd gone with the Black Ships when they called and been declared completely safe.

After all, if there's one thing the Imperium is famous for, it's having paper trails be more trouble than they're worth, so I'm assuming he could bluff his way past just about anybody.

On the other hand, it wouldn't hold up under direct investigation, and if anyone's likely to come under direct investigation by the Inquisition, it'd be a Rogue Trader.