How to split a PDF page into two programatically using Acrobat SDK in .Net

lrosenth is correct that you need to create a plug-in to actually spit a page into two, but there are at least two other options: You can license the Adobe PDF Library (which does come with a number of different interfaces, one of them being for .NET - you can license this library via DataLogics: http://www.datalogics.com/

Another option is to use a JavaScript to make the pages look like you split them into two by duplicating the page, and then cropping two different parts for both copies of that page. You can then call this JavaScript from your .NET code via the JSObject. You can see an example of how to do this in JavaScript here: Splitting PDF Pages - KHKonsulting LLC 

Do you mean take a single page and turn it into two pages? There are no APIs for .NET that can do that. You will need to write a plugin in C/C++ to accomplish that with Acrobat.