Integrating PDF Upload Functionality with PTC.CADDocumentMgmt API

When examining the PTC.CADDocumentMgmt API, I can use the endpoint http://serverName/Windchill/servlet/odata/CADDocumentMgmt/CADDocuments('OR:wt.epm.EPMDocument:24416953')/Attachments('OR:wt.content.ApplicationData:24416979') or simply http://serverName/Windchill/servlet/odata/CADDocumentMgmt/CADDocuments('OR:wt.epm.EPMDocument:24416953')/Attachments to view data within Attachments using the GET method. However, my objective is to add a PDF to Attachments, in other words, I want to use the POST method. I can see the GET Attachments, but I couldn't find a way to perform a POST on Attachments. How can I achieve this? There is a GET method for Attachments, but a corresponding POST method is not apparent.