Rick Snow's book might might have better info but the following is from the CPG. The mark was added to one die and used for a single day production run in order to catch a suspected Mint thief. It also notes that "the market value for this variety is not yet reliably established".
Assuming the die was taken out of service at the end of the day after the employee was caught, I would not imagine there could have been any more than 50,000 minted and that could certainly be on the high side. I am currently assembling a roll of 1875s and I do not have a single dot among the 20+ examples I own.