ABCpdf .NET Demonstration

First, create a bounding rectange on the document preview, below, by clicking to define a corner and dragging to define the opposite corner; or you can type coordinates into the boxes beneath the PDF preview. The rectange will be shown in light orange. Once you have defined a rectangle you can choose one of the following options to add an element to your PDF:

Left Bottom
Width Height

To see how this webpage works, and it really is quite straightforward, download ABCpdf .NET and look at the included example website project, which is what this website is running.