I had the ez squeeze company press it while at the last cannabis cup. They put the bud in parchment paper, flattened it with his hand before putting in the press. Squish bud, remove from press, toss flattened nugget, and gave the the rosin on the paper
Not sure of the yeild. I get damn good yeilds pressing my keif filled baggies. Yeilds I'm very happy with. Best guesstimate, 81g keif should net me 28g rosin, depending on temps pressed at. This is by judging what I've pressed so far, what yeilds I have currently, and how many 5g baggies I have left to press still.