One of the most popular features of EndNote is the ability to store full-text articles (usually in PDF format) with a reference. Notes and highlights can be added to your stored PDFs.
There are a few ways to locate PDFs and place them into EndNote:
1) Finding Full-Text PDFs . EndNote can try to locate and download the full-text PDF of your references, if the full-text is available through the library's subscription databases or for free on the web. When EndNote locates a copy of the PDF, it automatically downloads and attaches the PDF to the corresponding EndNote record. Note: This will not work for all PDFs
2) Attaching a PDF: Attach saved files from your computer to a corresponding record already in EndNote
3) Creating References from PDFs: Import saved PDFs into EndNote. If the PDFs have the appropriate metadata saved with them, EndNote is able to create new references in your library with all of the citation information for each article and simultaneously attach the PDF files. (Note: Not all PDFs contain the necessary metadata for this to work.)