Your picture isn't working for me, but regardless, we can't tell you how much of a compound you have on a bit of blotter. You need to ask the dealer what dosage was on it. If he/she doesn't know the dosage (e.g. purchased it from someone else), at the very least ask them what dosage they'd recommend, though if in any doubt I wouldn't consume it just in case.
A big blotter could be completely laced in the drug and have a very large amount of several mgs, or it could have as little as 500ug, the size doesn't represent the actual dose, though of course, the bigger the blotter, the more it can hold.
Since we can't help identify the amount of active compound and that's all your asking, there's not much else we can do to help here.
If you aren't able to find out the dosage it may be possible to extract the substance from the blotter and then weigh with an mg or mcg scale.
Since you're new, I won't close this right away, but rather let us know if you have any further questions, and if so I'll merge this with the
DOB Thread once they're answered, if not I'll close it
