Under FAA rules of you hold a PIC type rating ( not an SIC only type rating) you can log PIC for the time you are the Pilot Flying........The FO will log PIC for the time he or she is the PF......It really is that simple
Well, it is simple but (a)it means that I'm sitting next to someone who claims to have X 000 hours as PIC when they've got nothing of the sort and (b)it means I'm sitting next to another captain and he's claiming PIC hours from the right seat, when I'm the actual PIC in the left seat. Absolute bloody nonsense, no matter how simple.