If you are rated in the aircraft, you (as an SIC) can log PIC under FAR 61. The captain (person who signs for the aircraft) logs PIC under FAR 1 regardless of whether he is the manipulator of the controls. If you have both types of PIC, it is best to keep separate logbook columns since some companies (I'm look at you Jetblue and Southwest) only accept FAR 1 PIC.