Signing

This page explains where signatures come from, how you place one, and what saving does to it.

Getting a signature in

There are two ways to bring in a signature. Both end as a signature file with a transparent background, so it sits on top of a document instead of appearing in a white rectangle.

• Capture from Page… - drag a box round a signature already on a page, wherever it came from. The box is kept as a small PDF, so the strokes stay paths and scale without softening.
• Import from File… - a picture of one, kept as a PNG.

You are asked what to call it, and it is then available in every document. Show the Signatures Folder opens where they are kept.

Why capture from the page

Preview flattens a signature into the page when it saves. A signed document then has no annotation left to capture. Preview's own signature store lives in the keychain, which a sandboxed application cannot reach. Capturing from the page works because the page is always there.

Placing one

Choose a signature from the pull-down. It lands in the middle of what is on screen; drag it where it should go.

It is placed in the document you are working in. That is the pane the status line names, not necessarily the window's own document.

A placed signature is a mark

It is selectable, movable and resizable like any other mark, appears in the marks list, and undo takes it back. Putting it straight into the page would make it permanent the instant it appeared. That suits a finished document, but it gets in the way while you are still positioning it.

What saving does

Saving keeps the signature a mark. It stays movable afterwards. What saving adds is an appearance for it, written into the file after the save, so that Preview, Acrobat and every other reader draw it rather than an empty rectangle. The page's own content is not touched.

A signature is drawn into the page only when you make the marks permanent. See Making marks permanent.

What it is not

A signature here is a picture of your signature placed on a page. It is not a cryptographic signature. Like every mark made here, it carries your name and the time it was placed, which other readers show in their comment panes; that is testimony, not proof. For what a PDF password is and is not worth, see Protection.

If you want a copy where the signature cannot be lifted out by anyone who agrees to be stopped, see Making marks permanent.

Watch: a short video for this page is still to come.

Contents