Why are you reading a PDF file from the ancient Acrobat 8 SDK instead of the current SDK?
No, Reader is not enough. You need Acrobat. Adobe like to sell copies of Acrobat, they have the upper hand here.
You are missing something. That you need Acrobat. Please read about reader enabling in the SDK.
The essence is
- create the plug-in with Acrobat
- apply to Adobe for a Reader plug-in license
- if granted, pay the fee
- get a special key from Adobe
- prepare the Reader plug-in