I do not know a specialist, but as far as I know basically you need to:
1. have the top part of monitor on your eyes level
2.possibly shoulder support and 90 degrees between forarm and arm
3.90 degrees between hamstring and tibia, and hamstring support as far as possible
4. If your feet are not flat on the floor, put a support under them
5. Have a support under a lower back in form of a "bump" and also possibly full back support including head
6. Some people use keyboard and mouse pads with support, but I believe if you have huge hands like me, it is not necessary.
If you have back problems, then investing in automatic desk that permits to have standing office as well as sitting one, is not bad idea.
Btw. physio recommend nowadays standing up every 30 minutes.