The phrase "append a note" is correct and usable in written English.
It can be used when you want to add a note or comment to a document, message, or piece of information.
Example: "Please append a note at the end of the report to clarify the findings."
Alternatives: "add a note" or "include a note".
I also want to append a note on the Occupation, and its ills, that couldn't quite fit, thematically or spatially, into the printed piece.
If extensive corrections are made to an online article, editors usually append a note in italics pointing them out at the beginning of the story.
If there is no procedure in place to allow someone else to do the evaluation, your supervisor's next best alternative is to append a note to the evaluation explaining the awkward position in which she finds herself.
Friends and colleagues they shall remain anonymous who passed this e-mail along would append a note: "You should read this" or "The Angry American actually makes sense".
Perhaps that's because the iPhone app lets you take pictures using the camera, append a note and save it to your Evernote page, where it is archived and searchable.
At the least, he said, I should have appended a note "explaining the difference between a news story and a column of opinion".
When "Huckleberry Finn" was published, Mark Twain appended a note on his effort to reproduce "painstakingly" the dialects in the book, including several backwoods dialects and "the Missouri negro dialect".
Mistakes should not disappear silently, so we correct factual errors in developing news stories by appending a note in italics at the bottom of the article on the Web site.
Chelsea herself apparently appended a note saying that while she did not agree entirely with Ms. Morgan's point, she was starting to understand what older women were complaining about.
(Satie appended a note to "Vexations," stating that the two-minute-long piece should be played eight hundred and forty times, after the pianist has prepared himself "in advance, and in the utmost silence, through serious immobilities".
Lyndsey appended a note in which she called the article "a nice example of emerging scientific research by scientists clearly convinced they are doing something vital and important to help people with M.E., plus the inevitable institutional caution/resistance of someone who has made a career out of saying it's all psychological!" Lyndsey compared her condition both to M.E.
