Has anyone tried to use Adobe's SDK for editing PDF's?

I found the following code example, but I have no idea where or how I get the Acroexch class library. I've tried finding answers on adobe's website, but I simply don't understand. Not to mention they don't have any specific answers for VFP.

Any help would be appreciated.

AcroExchAVDoc = CreateObject("AcroExch.AVDoc") 
AcroExchAVDoc.Open('c:\vpmapps\tlp\myfile.pdf', '') 
AFormAut = CreateObject("AFormAut.App") 
Fields = AFormAut.Fields 
*-- Add a Text Field to the PDF, named Instructions. 
Field = Fields.Add("Instructions", "text", 0, 70, 740, 543, 790) 
*-- Set Font Size of Text Field. 
Field.TextSize = "72"