Certainly the 2REM local studio doing some work (and apparently has been since 1988), particularly because they give out the markets and dividends for both sides of the border before switching back.
When I caught a bit of it in the car a couple months back, and listening to it now, it sounds like they relied mainly on Sky Racing TV’s audio stream (which is also the “TAB Live” stream broadcast through RSN digital radio/web site). It certainly wasn’t RSN’s main stream nor Sky Sports Radio.
As for the regional frequencies: RSN re-added the 927 frequency back to their logo after they lost retransmission into Tasmania and Canberra when their TABs were sold off… they do still have the regional frequency map but they’ve hidden it under the “Sales and Research” tab for whatever reason. I’m guessing that regional punters would be able to find RSN on their radio fairly easily and they’re trying to push people towards their digital streams like Carnival.