Fingering for german system oboe

I'm trying to understand here, because Boehm didn't design an oboe. Are you talking about the Sellner or Wiener (Viennese) oboe?

Or do you have a regular oboe that is not full conservatory.

Here's a link to tell the difference:

https://www.yamaha.com/en/musical_instrument_guide/oboe/selection/selection002.html

If you do have a Wiener oboe, the fingerings are pretty close to a soprano recorder.

Definitely not a Wiener. Wiener oboes have a uniquely shaped bell and a bulb at the top. It won't take a regular oboe reed.

THe first oboe I used was a school instrument that did have a ring for the rh ring finger, but the fingerings were conservatory system.

That's a thumbplate, as reeddoubler pointed out. I did not know, however, that there was a boehm system oboe, but it's an even stranger critter.

https://www.virtuosityboston.com/caracassone-boehme-system-oboe-ca-1890-low-b.html

Here's an article that shows the difference between thumbplate and conservatory.

https://www.jpmusicalinstruments.com/news/conservatoire-thumbplate-or-dual-oboes-explained

...and last but not least, the difference in fingering:

"The two notes that are different from that chart (as it's for conservatiore system only) are Bb on middle line and the C above it, and the high Bb and C:

Bb: xxo|ooo Left thumb OFF thumbplate
C: xoo|ooo Left thumb OFF thumbplate

Bb and C in the upper register is the same, but open the 2nd 8ve key with the middle joint of your left index finger.

But you do need to keep your left thumb on the thumbplate for all other notes."

http://test.woodwind.org/clarinet/BBoard/read.html?f=18&i=23982&t=23982