Both the left and right hand should be Vertical at Impact. The left and right hands should be 'parallel' (palms facing each other). A good check with the left hand is to make sure the score lines on the clubface 'matches' your flat left wrist at the top of the swing.
But how can you be sure that the right hand isn't turned under or rolled over too much? It can be hard to tell...but I stumbled across something recently...
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