Forms and signing

How to Fill In a letter PDF

Updated 2026-09-17 · 2 min read

The usual reason to fill in a letter PDF is a recipient name, address or date on a letter you are reusing.

A PDF form either has real interactive fields or it is a flat picture of a form. Both can be completed properly without a printer.

PDFfont edits PDF text in the document's own embedded font — no white cover boxes.

Steps to fill in a letter PDF

Open the file and click a blank. If a cursor appears, the form is interactive — type and tab through the fields.

If nothing happens, the form is flat: add your own text boxes on the ruled lines and checkboxes in the squares.

Match the size and colour of your entries to the printed labels so the page looks typed rather than annotated.

Read it back, flatten, and save.

With this kind of document, letterheads keep their logo and margins untouched while the text is replaced.

One caution worth stating plainly: check the salutation and reference line both match the new recipient.

Flattening stops values being cleared or altered by whichever reader the recipient opens it in.

It has no interactive fields; add text boxes over the lines instead.

Usually yes, unless the recipient reads form data automatically.

Yes. The editor runs in mobile Safari and Chrome, with touch-sized controls and a share sheet for saving the finished file.

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