In LynxPDF Editor, you can easily adjust the paper size to match your printing requirements, whether you're using standard sizes like A4 or custom dimensions. Here's how you can set the paper size before printing your PDF.

For Windows: 

1. Open your PDF document in LynxPDF;

2. Tap Print at the top right corner, or hold Ctrl + P;

3. In the Print dialog box, select Page Settings;

4. Choose the desired paper size from the Paper Size dropdown menu.

For Mac: 

1. Open your PDF document in LynxPDF;

2. Hold Command + P;

3. In the Print dialog box, select Show Details;

4. Choose the desired paper size from the Paper Size dropdown menu.