In the USA Sorbic Acid is GRAS – Generally Regarded As Safe, and limits are GMP, Good Manufacturing Practices. This means you can put as much as you like, as too much will not have any benefit.
It depends on the composition of your formula and your processing, as well as the pH range you wish to target. I would suggest you start with a target pH at around 4.0 to see if this produces the results you need. Check with your supplier on the concentration they are providing you with and recommended usage levels.
Information on BAKERpedia about Sorbic Acid can be found here: https://bakerpedia.com/ingredients/sorbic-acid/
The US Food and Drug Information can be found here: https://www.ecfr.gov/cgi-bin/retrieveECFR?gp=1&SID=374eb1788f0f045c12bd21ff651f2194&ty=HTML&h=L&mc=true&n=pt21.3.182&r=PART#se21.3.182_13089
@baking-innovation ; Do you have any starting quantity suggestions?