How to read a PDF and take notes side by side on a Mac

Pick a PDF reader

• Preview (built in): highlights, text notes, shapes, signatures. View → Single Page or Continuous Scroll, and ⌘- / ⌘+ to zoom. Enough for most reading.
• Skim (free, open source): made for academic reading. Notes sit alongside the PDF in a panel and can be exported as text.
• Zotero (free): if the PDF is a source you'll cite, open it in Zotero's built-in reader so highlights and notes stay with the reference.
• PDF Expert or Acrobat (paid): if you need editing, forms or heavy annotation.

Side by side on a MacBook

On a 13- or 14-inch screen, a PDF at half width is small. Three things help:

1. Fit to width. In Preview, View → Zoom to Fit after resizing the window, or zoom until the text column fills the window. Two-column papers are easier if you zoom into one column at a time.
2. Uneven split. Give the PDF about two thirds and notes one third. macOS's own tiling only does halves; Rectangle, Raycast or a window manager give you thirds.
3. Hide the chrome. Hide the sidebar in Preview (View → Hide Sidebar) and the toolbar if you don't need it. See more screen space on a MacBook.

With an external monitor

Put the PDF on a monitor in portrait orientation if you can: a rotated monitor shows a full page at a readable size. See vertical monitor on a Mac. Notes go on the laptop screen.

Two PDFs and your notes

Comparing two papers, or reading a paper alongside its supplementary material, means three windows. On a laptop that's too many for side by side. Options:

• Open both PDFs as tabs in one Preview window (Window → Merge All Windows after opening them) and switch with ⌃Tab.
• Use a three-window split on a larger screen.
• Use a strip that scrolls (below).

A strip for reading sessions

A scrolling window manager is good at reading: every window gets its own column on a horizontal strip, and the strip scrolls. In Ribbon:

• Put your notes in a column a third wide.
• Put the paper beside it at two thirds.
• Open the second paper and it goes into its own column to the right. Swipe across to it, read, swipe back; the notes don't move.
• Stack two PDFs in one column (⌃⌥]) to have one above the other, or turn the column into tabs with ⌃⌥⇧T.

Try the strip in the live demo; Ribbon is $9.99 once for macOS 13 or later on Apple silicon.

Getting highlights into notes

• Copy with the source: select text in the PDF, ⌘C, paste into notes, add the page number.
• Skim exports notes and highlights as text or RTF.
• Zotero can turn annotations into a note attached to the reference.
• Apple Notes: drag a PDF in to keep it with your notes, or use Share → Notes from Preview.