Step-by-Step Guide How to Add a Checkmark to a PDF (Checkboxes + X Marks) If the PDF won’t let you click the checkbox, you’re not crazy — it’s usually not a real fillable form. You can still add a clean checkmark (or an X) exactly where it belongs and export a finished PDF that won’t … Continue reading How to Add a Checkmark to a PDF (Checkboxes + X Marks)