First, I went to the products website, in this case Lesco and looked up the spreader settings:https://www.johndeerelandscapes.com/home/spreader-settings.aspx
Then, I went to Scotts website and looked up spreader settings:http://www.scotts.com/smg/node2/SCOTTSCOM/lawn-care/lookup-spreader-settings/7800015-24900013-s
I cross referenced a product on the Scotts website that uses the same settings as one of those listed on the Lesco website and I found my settings that way.
In my case I was using Lesco Pre-M 0.86% 0-0-7 and wanted to apply 5.3 lbs/1000ft. My spreader was a Scotts Turf Builder EdgeGuard Mini with settings from 0-15. I found out by cross referencing that the Scotts Speedy Green 1000 and my spreader used the same settings. So I ended up using the recommended setting of 5.5, as listed on the Lesco website for the Scotts Speedy Green 1000, to apply 5.3 lbs/1000ft of pre emergent using my Scotts EdgeGuard Mini.
Hope this helps!