If the original patterns were reduced by 64% then the correct increase should be 1/.64 = 156%. However, I noticed that on my print window, the printer was reducing the page further to fit the printing on the page. That would explain the 173% enlargement scale.

To get the correct scale for whatever reduction your printer did, measure the squares then divide this into 2. Multiply by 100 to get the percent enlargement.

e.g. my medium squares printed at 1 5/32 inches (1.15625)
so 2/1.15625 = 1.73 or 173%

Adjusting the PDF display will not affect the size of the printing. It is the print window that is further reducing the size.

Having the newest Adobe Acrobat Reader is also critical. Those of us who creat PDF files usually have the newest and I have found that the older readers will not read the files created by the newer writers.