Skew is the physical orientation of the LNB/LNBF on the dish,or in some cases you skew the dish itself.Polarity is the selection of either horizontal or vertical polarized signals,or right or left in the case of circular polarity schemes.
If the LNBF rotation Skew offset is set following the directions found on page two of your install guide, the instructions are correct. Your meter's polarity skew calculation is NOT correct.
Standing in front of your dish, rotate the LNBF in the clamp so it is counter clockwise only 4 degrees. This is almost straight vertical.