Look at the body of the guitar. All Jackson Randy Rhoads guitars have the flying-V body shape regardless of the year produced. The majority of the Randy Rhoads guitars have a shark-fin V shape with one wing longer than the other. The iconic polka-dot guitar, however, is a standard flying V with both wings of the same length.
Look for the letters "RR" on either the neck plate or the truss rod cover, which indicate that the guitar is a Randy Rhoads model.
Find the serial number on the guitar, which is usually located on the headstock, truss rod cover or stamped into the last fret. The letters "RR" at the beginning of the serial number indicate that the guitar is a Randy Rhodes model. Non-custom Randy Rhodes models produced after 1990 have a serial number beginning with "UO."