It's not immediately clear to me where the Toonzone user got this information, but a composer called Henry Russell (real name Henry Russell Olson, pseud. Johnny Hillbrook) does exist.
apmnut has mentioned the same info in
this thread - maybe he can chime in.
edit: Yowp posted some more details in this 2009 blog post:
https://yowpyowp.blogspot.it/2009/12/capitol-hi-q-cartoon-music-for-huck-and.htmlHere's the full article from Billboard that is mentioned there:

I unfortunately I can't seem to find any direct copyright entries tying him to the "R" cues, so I can't really confirm it with certainty, but that doesn't necessarily mean it's incorrect either. Russell is credited for cues on the Gumby Show, so he's absolutely a likely candidate.
As always, the answer may very well be listed in the earlier edition of the Hi-"Q" catalogue, which hopefully will turn up any day now
