If you try to open a file from Sharefile MDX, for example a pdf in iBooks you will not have the choice for iBooks apps.
So you need to modify Document exchange (Open In) from Restricted to Unrestricted:
However, after doing that you will have the ability to open the pdf file in iBooks, but you will get this error:
To resolve this issue, you need to modify the ShareFile MDX properties, add \.pdf$ in File encryption exclusion under Encryption:
After that you will have the opportunity to open the PDF file in iBooks.
Note: Those information are provided based on my own experience.