That’s maybe the best suggestion.This function can be simple likes the app which called note-taking.There are more details following:
A highly user-friendly implementation would be to offer predefined margin options. Imagine a control panel where we could:

1. Select a margin width (e.g., Small, Medium, Large).
2. Select the sides to apply it to (Top, Bottom, Left, Right), with the ability to select multiple sides in any combination.
This would provide the flexibility needed for notes, while being much faster and more precise than freehand dragging.

This would be great! Also, I suggest GoodNotes adding a function to add even / odd pages with the corresponding margin directly on the right / left side so we can see the margin directly while writing.

Hãy thêm tính năng này giúp tôi với tôi rất cần nó . VD : Note+ đã có chức năng này dù nó miễn phí

Yes! That would be amazing!! I can't believe that almost 10 years after this post, it still isn't available!!

I hope the goodnotes devs will add this feature, but in the meantime the following command-line may help some people:
pdfjam --fitpaper true --trim "-5cm -5cm -5cm -5cm" input.pdf -o output.pdf

It adds 5cm margins on all pages of a pdf document.

Critical for me, in using Goodnotes to annotate work from clients

This will help so much for lecture notes in university!!

Making an account just to boost this! The only reason I bought the app was cuz my friends told me that it's got a search function and it imports pdf in really high quality compared to OneNote. However, I've got no space to write my notes in the margins. I've tried apps to resize the margins of the pdf but the resulting file is not compatible with GoodNote's search function.

A simple fix that I would be happy with would be to allow double page viewing, which is not the same thing as split window viewing. It would give me the equivalent of more margin space without resizing pdf.

Edit: I found a horrible workaround! In Windows you can use 'Print to PDF', set a larger paper size, and choose 'Advanced>Use original page size'. This creates a new PDF with a white margin to the right and below. Not ideal but let's face it, this feature will never get enough upvotes for consideration. Hope this helps someone!

I just jumped through hoops in order to sign up to this website simply so I could add my support for this idea.

Please let me expand the margins on imported PDFs! Let me assign a new PDF template as a 'background' for the PDF pages, so I can have plenty of room for notes. I shouldn't have to use a separate piece of software to edit PDFs in order to make them easier to use in Goodnotes.

This would be awsome because i have books where I would like to add annotations and its hard to fit withing the pfd form

THIS!!! I need this so badly. I don't usually have enough room on the slides to annotate, and even when I do, it all just gets crowded. While I can always add an extra page, it's just so much easier on the eyes writing to be able to write things on the side.

I know about the turn-a-page-into-an-image technique but it’s just a hassle and you have to keep the old page anyway if you need the text for search and copy functions. I’ll do it for a few pages but I work with multiple textbooks and I would be forever thankful if we got a better solution.

If done right, this could also potentially help to unify slide formats. When importing from PDFs of different sizes and adding manual Good Note Slides. That would help a lot.

Yes, please add this!!! It woudl be a game-changer (super important) for taking notes on lecture slides.

Yes, please! The pdfs I'm using sometimes do not have enough margin :(

This would be amazing! It’s not enough to copy + paste the page onto a different sheet and write around that. We need a way to add actual borders to the document so the text size is the same!

Please add this feature asap.

OMG PLS THIS WILL ACC CHANGE THE AMOUNT OF QUALITY ASSURE LIFE YEAR I HAVE
IF I COULD IMPORT A DOCUMENT E.G LECTURE NOTES AND THEN ADD A MARGIN/ COMMENTARY PANE I WOULD ACC BE SO HAPPY. THANK YOU . PLEASE PLEASE PLAEASEEEE

It's something I've struggled with for a long time! I'm in a major that requires me to read a lot of texts, and many PDFs I'm provided with do not have sufficient margin spaces on either side for me to annotate. Including an option to annotate in spaces outside the PDF (like OneNote) would be really helpful.

The reverse would also be helpful, if I'm reading a PDF that came with large margins and I decide I would rather have larger text than more note-taking space.