Smart-rings are ideal for subtle and always-available haptic notifications due to their direct contact with the skin. Previous researchers have highlighted the feasibility of haptic technology in smart-rings and their promise in delivering noticeable stimulations by poking a limited set of planar locations on the finger. However, the full potential of poking as a mechanism to deliver richer and more expressive information on the finger is overlooked. With three studies and a total of 76 participants, we informed the design of PokeRing, a smart-ring capable of delivering information via stimulating eight different locations around the index finger's proximal phalanx. We report our evaluation of the performance of PokeRing in semi-realistic wearable conditions, (standing and walking), and its effective usage for information transfer with twenty-one spatio-temporal patterns designed by six interaction designers in a workshop. Finally, we present three applications that exploit PokeRing's notification usages.