please note, for all the current VOSS based switches you have to use this MIB tree to get access to the system resources. (RapidCity MIB)
Several example above are wrong, because they pointing to the Synoptics MIB!!!!
Here the details about CPU utilization
Name: rcKhiSlotCpuCurrentUtil => OID: 126.96.36.199.4.1.22188.8.131.52.1.1.2
Description: Percentage CPU utilization under current