Green’s Dictionary of Slang

right on! excl.

[abbr. earlier right on T/right on time; the later use implied movement/progress rather than chronology]

an excl. of encouragement, approval: excellent! perfect! exactly right! orig. black use but taken up by white hippies, radicals etc.

[US]Journal of Amer. Folklore 24 292: Railroad Bill was [a] mighty sport, Shot all [the] buttons off [the] high sheriff’s coat, Den hollered, ‘Right on, desperado Bill!’ .
[US]Odum & Johnson Negro and His Songs (1964) 202: Railroad Bill was a mighty sport, / Shot all buttons off high sheriff’s coat / Den hollered, ‘Right on, Desperado Bill!’.
[US]B. Seale Seize the Time 122: A lot of the brothers said, ‘Right on time. Huey. Tell it. Right. Run it down, Huey.’.
[UK]J. Mandelkau Buttons 90: The whole house was full of naked people getting it on. Right on, brother!
[SA]R.M. Kavanagh Survival in Kavanagh S. Afr. People’s Plays (1981) 143: Right on, brother Vusi.
[UK]T. Blacker Fixx 102: Never trust anyone over thirty? Right on, man. I could dig it.
[US](con. 1960s) G. Washington Blood Brothers 8: Right on, baby, right on.
[UK]L. Theroux Call of the Weird (2006) 164: Right on, man! Keep this town real!