Hello Torbjorn,
Adobe LiveCycle Reader Extension ES will activate this feature. If you want users to be able to do more than simply read a PDF document or submit XML data file you'll need to install LiveCycle Reader Extension. Adobe LiveCycle® Reader Extensions ES software, allows you to activate functionality within Adobe Reader (version 7 and above), enabling end users to save, fill in, annotate, sign, and submit PDF documents and forms online or offline. LiveCycle Reader Extensions ES works with existing IT assets to create an automated environment for capturing information and feedback.It allows you to embed usage rights within an Adobe PDF document. These usage rights "turn on" functionality within Adobe Reader, so end users can view and interact with PDF documents.
Features & Benefits:
http://www.adobe.com/products/livecycle/readerextensions/features.htmlTrial Download:
http://www.adobe.com/devnet/livecycle/trial/LiveCycle Reader Extensions ES Overview(Page 37-39):
http://help.adobe.com/en_US/livecycle/es/overview.pdfHope this helps.