I would like to know which cannon could have fired such a shell and what does the R stand for? Was it fired in WWI?
The dimensions are as follows: length 58 cm, width at the base 9.5 cm, and width at the top 8 cm. Are they rare?
The shell was manufactured in 1910 at the Wöllersdorf Works factory at Berndorf in Lower Austria (and nicknamed 'Krupp-Stadt' or 'Krupp city', which should give you some idea of what they're famous for!).
Shells manufactured in 1910 could certainly have been fired during the First World War.
The dimensions you've given look to be a pretty close match to the round for the 7.7 cm Flak L/35, (77 x 586R). However, the 1910 date looks to be very early for that.
For what it is worth, the Western Front Museum web site says they have one of these in their collection - although they designate it as the 8 cm Flak L/45K. Unfortunately, they don't have a picture on their web site, but it may be worth contacting them.
As for the 'R' stamp on German / Austrian munitions, that is a new one to me. I'll need to do some more research there.