Hello
I tried first for the family of John Shepherd. The only one that seemed likely in the area was born in Witney 1766, but appears to have died in infancy. No others close to Taynton at about the right age. (You may have to try GLO parishes as Taynton is on the border.)
I couldn't find John's burial either - it might have given us his birth date.
His wife Priscilla was buried 10th Nov 1842 aged 76 at Taynton. Annoyingly it doesn't say either "widow" or "wife of" so we don't know which of them died first.
Also I couldn't find the baptism of Priscilla's parents, although my hunch is that Stephen was the son of John & Elizabeth Pittaway (marriage not found)who had children baptised at Taynton between 1724 and 1735 - perhaps his baptism was accidentally missed out of the register.
Stephen was either buried 31st March 1779 or 10th May 1807 at Taynton. His and Zipporah's last child was baptised in 1779, so I would guess the former.
Zipporah was buried 2nd Jan 1801 at Taynton (no age given).
As for Zipporah's baptism, the baptism database has only one Rickens countywide (a William at Henley in 1807). I tried variants such as Ricketts, but with no luck.
You were probably expecting a lot more - sorry, I fear the answers (or some of them) lie in GLO and I only have access to OXF information here.
Regards
Mick