I noticed that a8detective mentioned in the submission notes for SF 1010 that the Sam Fox listings could be dated using RCA master serial number codes.
discogs.com/release/2367759-Untitled/history#latest
An RCA pressing from Rockaway is apparently indicated by the small R in the matrix mentioned here. As far as I can tell from my Sam Fox issues at least the early ones have a small R.
discogs.com/label/461373-RCA-Records-Pressing-Plant-Rockaway
Going off of the mentioned link under the subheading of:
"III. 1963 - 1990's
Upon RCA's adoption of the infamous "Dynagroove" system for cutting records, they instituted their third and last revision of matrix number codes"
discogs.com/forum/thread/694503
Unfortunately, the Discogs submissions do not all have the matrix numbers for the main SF catalog though the images appear to have them printed under the RPM indicator. The last four digits are kind of arbitrary and seem to indicate the individual ID number for the each side's master.
0(Sam Fox Catalog No.) 1(Year Code), 2(Label Designation), 3(Size and Speed), 4(Groove)
SF1001 R 4RM - 4494 => 1964 Re-recorded from client's furnished tapes 12" - 33⅓ RPM Mono (Fine)
SF1002 R 4RM - 4909 => 1964 " "
SF1003 R R4M - 0226 => 1964 Transpose typo? " "
SF1004 R R4M - 4665 => 1964 " "
SF1005 R R4M - 5536 => 1964 " "
SF1006 CO 5999 (doesn't follow RCA convention?)
SF1007 S 4RM - 0530 => 1965 Re-recorded from client's furnished tapes 12" - 33⅓ RPM Mono (Fine)
SF1008 S 4RM - 6250 => 1965 " "
SF1009 S 4RM - 6411 => 1965 " "
SF1010 S 4RM - 9092 => 1965 " "
SF1011 T R4M - 1203 => 1966 Transpose typo? " "
SF1012 T R4M - 1664 => 1966 " "
SF1013
SF1014
SF1015 T R4M - 5940 => 1966 " "
SF1016 U 4RM - 8794 => 1967 Re-recorded from client's furnished tapes 12" - 33⅓ RPM Mono (Fine)
SF1017 W 4RM - 0274 => 1968 " "
SF1018 W 4RM - 1150 => 1968 " "
SF1019 W 4RM - 1901 => 1968 " "
SF1020 W 4RM - 2138 => 1968 " "
SF1021 X 4RM - 0751 => 1969 " "
SF1022 X 4RM - 0809 => 1969 " "
SF1023 X R4M - 1726 => 1969 Transpose typo? " "
SF1024 Z 4RS - 448-2 => 1970 Re-recorded from client's furnished tapes 12" - 33⅓ RPM Stereo
SF1025 Z 4RM - 1151 => 1970 " " Mono (Fine)
SF1026 B 4RS - 0051 => 1972 Re-recorded from client's furnished tapes 12" - 33⅓ RPM Stereo
SF1027 B 4RS - 0008 => 1972 " "
SF1028 CO 5493A (Printed date of 1973)
SF1029 CO 6134A (Printed date of 1973)
SF1030 (Printed date of 1974)
SF2001 W 4RM - 1645 => 1967 Re-recorded from client's furnished tapes 12" - 33⅓ RPM Mono (Fine)
SF2002 N O8P - 0910 (doesn't follow RCA convention?)
And a random Demeter for good measure.
D 17 T R4M - 1373 => 1966 Transpose typo? " "
A lot of the matrix numbers switch the second character matrix numbers 4RM to R4M. According to the discogs thread, "RCA Victor Master Serial Number Codes - 1942-1980's":
4RM would indicate "Re-recorded from client's furnished tapes" and "12" - 33⅓ RPM".
R4M latter indicates RCA Red Seal Release and nothing viable for a "4" as the third character.
It would be very strange that a number of Sam Fox releases would be associated with the celebrated RCA Victor Red Seal title. It could be a typo for the R4M or some style change which causes the letters to become swapped once a year?
Anecdotally, from the magneticmusic.ws/Frame.htm link above, there are dates for
SF1020 => 1968
SF1022 => 1968
SF1025 => 1970
SF1028 => 1973
These dates do match up with the RCA matrix codes except for SF1022 which is off by a year.
Checking by another method, I did directly find from SF1001 Loren Wilfong's "Colloquy For Bass And Bongos" registered in the 1964 edition of Catalog of Copyright Entries: Third series in Google Books. A spot check of other titles did not turn up any other entries from the Copyright Catalogs in Google Books though I haven't yet checked the actual US Copyright Office. Still the 1964 date agrees with the matrix for SF 1001.
Other thoughts:
I am missing a handful of catalog numbers, but it can be interpolated.
5 LPs a year from 1964-1966. One LP in 1967. Slowly dwindles from 4 to 2 a year from 1968-1973. 1971 is skipped entirely.
The Golden Group (SF2001) LPs seem to have been produced during the lean year in 1967 with SF1016. It fits with the lower bound of Retronic's Sam Fox catalog shown further up the thread.
SF1006 is an early outlier and seemingly not pressed at RCA.
Sam Fox seems to have stopped using RCA by 1973 and SF1028.
The RCA matrix dates could be extended to Sam Fox's other labels: Demeter, OK Music if the small R appears in the matrix.