Using PrintMultilineText or PrintText works as expected but it adds a blank page in between the pages.
Solution: Add a page number to SetFont method
Change
oTK.SetFont("Arial", 11f)
to
oTK.SetFont("Arial", 11f, -1)
(-1 = all pages)
or Remove the SetFont call if not needed.
See Toolkit.TextStamp.cs example