"The people of Antioch (dedicate) to Caesar Augustus, priest at Antioch, the appropriate archieretic wreath." - Refers to the acception of the title archiereus by Augustus. Obv. and rev. legends should be seen together:
KAISARI SEBASTW ARCHIEREI ARXIERATIKON ANTIOXEIS
ANTIOXEIS = subject of the sentence = "the people of Antiochia"
KAICARI SEBASTW ARCHIEREI = dative object of the sentence = "to Caesar Augustus, the Archiereus" (added: "dedicate")
ARXIERATIKON (added STEPHANON) = accusative object of the sentence = "the archieratic (wreath)"
The Actian era is counted from the battle of Actium.