I don't recognise this idiomatic usage, but there are a dozen or so instances of top/topping it the knob/nob in Google Books - so in a limited sense, the expression does exist. But that link is typical for all verb forms and spellings - they're mostly novelist Patrick O’Brian, from 15 years ago or less.
I suspect this use of to top [it the something] relates to OED's sense 15:
Theatr. to top one's part, to play one's part to its utmost possibilities or to perfection; to transcend the character assigned to one; transf. to sustain (a character) with success. to top the officer (Naut.)
Thus, "to top [it] the xxx" can be seen as being related to:
"Don't come the high and mighty"
"He's always playing the fool"
"I'll just act the innocent"
I also suspect "knob" is always incorrect here, since I'm pretty sure the nob being referenced is noun - Chiefly British Slang. a person of wealth or social importance. Since I find no evidence of "top it the [noun]" being used earlier than a couple of decades ago, I doubt it's "archaic". It's either a (deliberately or accidentally) garbled version of "top the [noun]", or an obscure dialectal usage.