From The Document Foundation Wiki
- create or open your document, presentation, spreadsheet, etc. in LibreOffice. All document types available in LibreOffice are supported;
- go to ▸ ▸ ;
Create a PDF Hybrid Dialog
- check to insert the LibreOffice editable file into the PDF;
- you can also change the other parameters such as compression, image resolution, watermark, etc. Do not forget that large images make for large documents; and
- click the Export button to complete the save operation (choice of folder and filename).