What has worked best for me after working with a number of apps is Create a document using Pages.
Share with iWorks.
I can login to iWorks and download as Pages, PDF document type.
I can access the downloaded document using ReaddleDocs and open it back in Pages again.

I can’t find a logical way to share out of iAnnotate other than wifi sharing or uploading to iTunes which seems like more steps than most people will want.