How can I insert note for merged PDF for later use?

Very easy as below steps show:

1. Click "File->Add/ Add a Directory" to add PDF files to the list;
2. Right-click on the file you want to add comment, choose "Comment" from Context-Sensitive Menu, and then input your comment in the pop-up "Input" box, click "OK" to save it;
3. Click "File->Export List" to save files with added comments as a Merger List file, when you want to use the comment added files later, just click "File->Import List" to add the list for loading them directly;
4. Define "Merge Method" for files and click "Merge" to complete the operations.

View video tutorial here: