How to add your signature to a PDF

Adding your signature to a PDF takes a minute in PDF by Zaweba, a free offline PDF editor for Windows. Open the document, choose Form, then Fill and sign, then Signature. The first time, you make the signature by typing it, drawing it, or choosing a picture of it, and after that you simply place it on the page.

This is the everyday kind of signature, the one that looks like your handwriting on a letter, a tenancy form or a permission slip. It is different from a cryptographic digital signature with a certificate, which the app also does from its Sign menu.

Making your signature the first time

When you pick Signature for the first time, a window asks how you want to make it. There are three ways, and each suits a different person.

Typing is the quickest. You type your name and the app shows it in a handwriting font that comes with Windows. It looks tidy and is fine for many informal documents, though it won't look like your real hand.

Drawing lets you write it with the mouse or, much better, with a pen on a tablet or touch screen. Take two or three attempts if the first is shaky. A slow, steady stroke gives a cleaner result than a quick flourish.

Choosing a picture is the best option if you want your real signature. Sign a sheet of white paper with a dark pen, take a photo or scan it, and crop it close in any picture editor before you load it. The app shrinks the picture to 900 pixels across and keeps any transparency, so a PNG with a see-through background sits on the page without a white box around it.

Your signature is kept on this PC only. It isn't sent anywhere and there's no account to sign in to. If you ever want a new one, Change my signature or initials replaces it.

Placing it on the page

Once it exists, choose Signature again and place it on the page. You can do the same with Initials, which is handy for contracts that ask you to initial every page. Place each one, then move or resize it until it sits neatly on the line.

Fill and sign works on any PDF, including flat forms that have no boxes to type in. The same menu has Add text, Today's date, Tick, Cross, Dot and Line, so you can fill in your name and the date beside the signature without hunting for another tool. The mark tools stay in hand, so ticking a column of boxes is quick.

Saving and sending it on

Until the document is flattened, each item you add stays a separate annotation that you can still move or delete. By default, saving flattens Fill and sign items into the page (this is a setting you can change), and text you typed becomes real text in the file. If you want to keep things editable while you check them, turn that setting off, then flatten when you're happy. There is also a Flatten fill and sign command that does this for Fill and sign items only, leaving any other comments alone.

Flattening matters when you send the signed copy to someone else. A loose annotation can be moved by the next person who opens the file, while a flattened signature is part of the page.

Making it look right

Size is the most common thing people get wrong. A signature that fills half the page looks odd, so shrink it to roughly the height of the text on the line. Zoom in before you place it so you can line it up properly.

If you scanned your signature, a crisp, high contrast photo matters more than a large one. Grey paper and shadows show up as a grey box. Good light and a dark pen fix most of that.

For a document that needs proof of who signed it and that nothing changed afterwards, use a digital signature from the Sign menu instead, or as well. A picture of a signature shows agreement; a digital ID can be checked by a program.

Because PDF by Zaweba works offline and keeps your signature on your own computer, you can sign private papers without uploading them to a website. Set it up once, and signing the next form is a couple of clicks.