One very important feature of Aloaha is the capability to use an existing PDF Template as Letterhead/Stationary for the generated PDF Document.
Please also have a look at: Apply PDF Letterhead/Stationary
You can see an HowTo Movie on Youtube below:
In case you want to apply a letterhead / stationary via hotfolder please have a look here:
http://www.aloaha.com/2017/12/01/batch-assign-letterhead-to-existing-pdf-documents/