Text Size, Font, and Font Style and click Done. If you prefer the more refined option of using Previewer, which is included in the Mac App Store, that's also available here and is fully compatible with Preview on Windows. How to watermark PDF on Mac (Windows) How to Add Watermark to PDF on Mac (Windows) · Step 1. Open your PDF file on Preview Pro. Step 2. Click Edit > Watermark > Add. You can select any of your PDF files on preview for this step. Step 1.1 If you want watermark on both sides, Click the menu button, choose Toolbars, and choose Watermark. Click on the menu button again, choose Options, and choose To add Watermark in the drop-down. Choose the text you want to add; In the top toolbar, choose Tools>Edit PDF> Watermark> Add. Specify the watermark you want to add. Click Save. How to Add Watermark to PDF on Mac (Windows) Step 1.1 Open a PDF. Step 2. Click on the menu button (bottom right) or double-click on the file in the browser. Step 2.1 in the menu bar click Show, choose Preview. Step 2.1 in the Preview bar next the button choose Watermarks tab and choose To add tab. Step 2.1 In the Watermarks' dialog box, Click the Add Watermark button. You can specify up to four watermark images or watermark text. Step 2.2 The image file is in the Documents\My Documents\PDFs folder. Step 2.3 Select the one you want to watermark in the drop-down. If you have multiple watermarked files there is only space for a few images. Step 2.4 You can add watermark text by clicking on the pencil icon. Step 2.5 Click on 'Use Text' under Add button to enable watermark. Step 2.6 When you click done, watermark is added. Click Save when you are finished. How to Add Watermark to PDF on Mac (Windows) How to Add Watermark to PDF on Mac (Windows) · Step 1. Open your PDF file on Preview Pro. Step 2. Click Edit > Watermark > Add. Step 2.1 Click on the 'Use Text' button to select the text you want to add. Step 2.2 In the Watermarks' dialog box, Click the 'Add Watermark' button.