Work out how much fluid a sheet of blotter holds. You want your solution to have that volume and contain 500ug x the number of individual blotters on the sheet. Then absorb it into the sheet of blotter. I've never laid blotter, though, and I'm sure there's more to it than that. For one, I don't know how you avoid the doses at the edges of the sheet ending up more potent than those in the middle. Please, everyone, be careful, if you're not 100% confident that you know what you're doing then don't do it.
Thanks for the info. Would love to hear from somebody who's actually laid blotter with this stuff though. As I said, I want to be as safe as possible. Obviously I don't want to harm myself, so I'm taking every cautionary step possible. If someone could chime in and help me out a bit more, that'd be great.