1. Create render in Poser.

2. Save the render as PSD, TIFF or BMP. These are loss-less compressions. 

3. Load the image into your paint programme, photoshop, paintshop pro etc.Postwork as desired.

4. In your paint programme, you literally print the image to .PDF using Adode Acrobat or other PDF creation software. Just google "Free PDF creator"..

5. Adjust compression levels accordingly in the PDF software and apply security to the PDF if needed. 

notes: 
adobe acrobat reader only reads PDF doesn't create them. 
Some free .PDF printers don't have compression or security settings. watch for spyware.  

Vince3 is correct you could easily make a scrollable e-zine by using one long image. 
Though it's best to 'print' each page seperatety and add them together as pages in something like Acrobat. It's a 10 second job.   

security - even with the right security settings most PDF's can have the images extracted if you have the right tools. Zoo publishing the makers of 3dcreative use the best security system yet. Thats unbreakable so far.   

EXPERT TIP ...
Another neat trick of Adobe 7 and higher PDF's is to embed real 3d models in them. Though the filesizes are massive.  Extracted models from PDF's are next to useless, though can be used as lowpoly background objects. If you need to show real time interactive models not renders  
Wirefusion is the best.system.   

Pinky - you left the lens cap of your mind on again.