Insert documents in the Sidebar. Also find these features on the Edit menu.
Existing documents can also be inserted in the current document, or appended to it. To insert a document, select the page following which you want to insert the document and choose Document Insert Document. To append a document to the end of the current document, choose Document Append Document.
Select a single file or multiple files. If you had more than one PDF document open in PDF Annotator, you will find the option to select any (or all) of those documents using the Opened in PDF Annotator option. If you selected multiple documents, arrange their order using the Up and Down buttons before pressing OK.