In that sentence, the penultimate の serves what grammatical function?
It softens a pointed question (の as an end-sentence particle is somewhat feminine-sounding, but のか is generally used by men). The end result the way I see it, though (and this is just an opinion here), is that it makes the question pointed just by being there
Now, depending on circumstance (such as who spoke it to whom), it could be someone’s normal way of asking a question and they mean nothing special by it (some anime characters overuse it as a personality trait), or it could mean that the one who said it isn’t necessarily trying to offend, or it could mean it’s a grisled vet saying this trying his hardest not to facepalm. The sentiment is something like “You are
reading the WAP manual, right?” (the proper tense to use for translation might be different; it could just as easily mean “have read” or “do read”). Usually, the use of the のか at the end of the sentence puts the emphasis on the verb rather than other parts of the sentence, and this is no exception.
There is no real way to tell what this means without knowing what’s going on. I mean, I could take a stab at what it probably means, but it could be very much incorrect. The reason is that the second sentence is incomplete. Without knowing what’s going on, it isn’t possible to reconstruct the sentence, translate it, then gut the appropriate parts to make it vague again.