Hi there,
Really depends on how your company QRH is structured.
In my company these cklists are split in PF-PNF actions and Cap-Fo actions.
Example: On the ground the Captain is always the PF (even if is the FO sector), so if during taxi out we have a fire bell the captain will stop the a/c and ask to state the malfunction-verify and call the FO-PNF for the appropriate QRH-recall actions.Then if we decide to evacuate the actions to be taken are split in Capt and Fo recall-actions and the captain is the one shutting down the engines and pulling the fire handle.
In flight a different story, the PF-PNF logic apply for cklists apart for the emergency descent one(in my company) where its clearly stated that the Captain assumes the PF role,this is valid for the RTO procudure as well.
Hope that helps!!