Detailed pay tables are included in the irrregular infrequent editions of
Air Ministry "The King's Regulations and Air Council Instructions for the Royal Air Force" (Air Publication 958).
My 1943 edn had pasted in amend slips in profusion, incl over the pay scales, in such a way the underlying earlier states could be seen readily. No longer have it.
I don't recall how far back the scales were dated as published.
Long-winded way of saying perhaps a later edn than c 1923 would do, but read on...
As you're in Brisbane, for Australia,
WorldCat.org appears to show 2 1930 edn copies in "Libraries near Sydney" but the underlying links seemingly broken, so no idea where. Huh.
Aus War Memorial Research Centre Library has two Edns listed, 1943 and 1938.
With major rebuild underway, unsure, didn't check, how accessible the AWM Research Centre is at present...
See AWM.gov.au etc.
National Library of Australia: no copy of any edn in NLA, however...
NLA Trove reports there are two copies of the 1924 Edn at State Library of Victoria.
Either follow the borrow link there or
go to https://www.slv.vic.gov.au/ and follow the Catalogue
I've found the Vic State Library v helpful in the past, using InterLibrary Loan twice at least to access books not otherwise accessible to me in here in Canberra. Forget the costs involved but well below the price of the book in question or fare to Melbun.
Couldn't spot any online scans of KR&ACI, though there could be.
No for sale copies on Bookfinder.com at present.
For comparison the c1943 booklet "The ABC of the RAF" had current war-time pay scales +allowances. Numerous copies of that around.
best wishes with the research