Hello stefano rigazio,

If I'm not getting wrong your meaning, you would like to let the user download the blog post as PDF format right?
If yes, you follow my step and configure it :
Step 1 : Download the Phoca PDF Component from here http://www.phoca.cz/download/category/32-phocapdf-component
Step 2 : Enabled Integrate with PhocaPDF >> http://screencast.com/t/CQxQVv254VB and download the EasyBlog PhocaPDF Plugin from our side http://stackideas.com/downloads/ and install it.
Step 3 : GOTO > Plugin Manager > Enabled "Phoca PDF - EasyBlog"
Then it should be work fine.
If you need further assistance, please provide us with your Joomla backend and FTP access so we can help you configure. Please advise.

No, I would like to port to attach a pdf file and make sure that the user can download.
Basically I would like to upload an attachment in the post, freely downloaded by users

Hello stefano rigazio,

Yes, you can upload your PDF file in the Easyblog Media manager, but you need to make sure that your Easyblog media uploader allowed extensions should set pdf, check my screenshot : http://screencast.com/t/fOPRoPnoeEgj
After you upload your pdf file in the media manager, so you can insert the pdf file in your blog post, so all the user also able to view this pdf file and download it. Hope this help.
>> http://screencast.com/t/X9bfdQ7K5