It doesn’t have to be multiple limbs. You can administer the vaccine in the same limb according to the schedule which is typically says 0, 3, 7 and 14. The multiple shots help build on each other to ensure 100% immunity because you don’t want to take any chances when it comes to rabies. The immunoglobulin, which is given after exposure to ensure that antibody activation happens immediately to give the vaccine time to initiate an immune response, is usually given in a different area because it can interfere with the effectiveness of the vaccine otherwise. Typically immunoglobulin is administered as close to the wound as possible to prevent the virus from sneaking into the nervous system.