The Edit Documents section actually uses html code which we then translate directly into pdf code. Because there's not a translation for everything, we've had to limit what could be done with the document editor. We will be adding more into this soon though as we've found a few work arounds to the PDF limitations.
For those of you trying to add images now. To the right of the font size is an invisible button. If you hover your mouse to the right of the font size button but centered with the button you will see a little button popup that you can click on. This button reveals the source code for the document. Here you can directly add images.
For example, here's a logo I have in my HIP directory. The <div align="center"> is for centering the image. Note the full path to the image is used for the src.
<div align="center">
<img align="center" src="C:\Program Files (x86)\Home Inspector Pro2\Data\Documents\logo.png">
</div>
Then hit the invisible button again to switch back to the normal editor.