1. Open the pdf file to be adjusted, and click Tools Options in the upper right corner.

2. Click the small icon "Show or Hide Panel" in the upper right corner of the Tools menu panel.

3. Select Print Production from the drop-down menu that appears, and a new line of options will appear in the toolbar.

4. Find and click "Set Page Box".

5. Find "Change Page Size", and then click the drop-down menu to adjust to the required page size.

First, you need to install a Fuxin reader on your computer. After the installation, open the PDF document, click the "File → Print" button (or printer mode, or Ctrl+P), and then adjust the PDF page size in the "Properties" to confirm the use of the printer.