If you have a raft you should stay attached to the foundering vessel via the painter line, a watch should be assigned with a painter cutter to cut the painter line if the vessel proceeds to sink. There should be a cutter in with the survival kit included with the raft, but you should verify with the company that repacks your raft. Remember to take your epirb with you in the raft or attach it to the raft and not the foundering vessel.
One thing to remember is that your vessel could capsize very quickly and if the raft is stowed somewhere you may not have time to deploy it. So make sure that as the captain you assign someone to be the person that gets the raft in the event of a problem while your send out a distress call or handling other issues that arise.