Hi Barbara,
Thank you for your interest in syncfusion products.
We can set the page scale using the scaleTransform method in PdfGraphics class.And we can manually set the page size in following units:
1.Point
2.Inch
3.Document
4.Millimeter
5.Pixel
6.Centimeter
7.Pica
Could you please look into the sample from the below link.
http://help.syncfusion.com/samples/pdf/HelloWorld.zipRegards
Meiyappan