Reference star differential imaging ( RDI ) is a powerful strategy for high contrast imaging . Using example observations taken with the vortex coronagraph mode of Keck/NIRC2 in L ^ { \prime } band , we demonstrate that RDI provides improved sensitivity to point sources at small angular separations compared to angular differential imaging ( ADI ) . Applying RDI to images of the low-mass stellar companions HIP 79124 C ( 192 mas separation , \Delta L ^ { \prime } =4.01 ) and HIP 78233 B ( 141 mas separation , \Delta L ^ { \prime } =4.78 ) , the latter a first imaging detection , increases the significance of their detections by up to a factor of 5 with respect to ADI . We compare methods for reference frames selection and find that pre-selection of frames improves detection significance of point sources by up to a factor of 3 . In addition , we use observations of the circumstellar disks around MWC 758 and 2MASS J16042165-2130284 to show that RDI allows for accurate mapping of scattered light distributions without self-subtraction artifacts .