Pretty self-explanatory title. I asked this in my local community chat and got answers in both directions. And yes, this is for PFS. I debated whether I should bring the issue up here or over on the PFS boards, but I figured someone over there would flag it for this forum anyway.
One suggestion was that I could only roll skills where the situation can be explained to the phantom, since it doesn't actually sense anything on its own and has to do everything purely on a mental level. This would include some Knowledge skills but not much else. Another suggestion was that the phantom could aid another on some checks, although I can't actually think of any skills this would apply to. Another was of the opinion that since the phantom offers two Skill Focuses, it doesn't roll any skills of its own. I'm expecting the answer to be that last one.
The main reason I'm asking this is due to the exciter archetype, which loses the ability to manifest. It'll be interesting to figure out what the phantom does exactly in this case.
Last time I asked about a rules question here, someone pointed out the answer was in the sourcebook, so I'm half expecting someone to point the answer out for me directly...
I'd say that if you can converse with your phantom while it's in your head then it can roll purely mental skill checks, but only with proper context. Saying "What do you know about X?" would work, but "What is that object/creature there?" would not.
The rules on how sapient phantoms are are extremely vague at best, though. I'm not sure how PFS runs them.
A phantom has Int 7 and is sort of formerly a person, and they're an outsider (for some reason) instead of undead, so I don't see why they couldn't have their own intellect - just very strongly colored by their emotional focus. I mostly play with the same GMs, so I'm willing to discuss this on a case by case basis with each of them, but it would be nice to have some sort of semi-official consensus.