PDF signatures can be specified using the xf:signature annotation property. Referencing an annotation containing this property from a visible element will convert the referenced element to a visible PDF signature, while referencing it from the fo:root will just add an invisible signature.
Example of usage:
<?xml version="1.0" encoding="utf-8" standalone="no"?>
<fo:root xf:annotation-reference="7" xmlns:fo="http://www.w3.org/1999/XSL/Format" xmlns:xf="http://www.ecrion.com/xf/1.0">
<xf:annotation id="7">
<xf:signature timestamp="06/17/2009" name="Jose Maria Gonzales" location="Granada, Spain" reason="Validacion" certificate-serial-number="01"/>
</xf:annotation>
<fo:layout-master-set>
<fo:simple-page-master master-name="all-pages" page-width="8in" page-height="11in">
<fo:region-body region-name="xsl-region-body" column-gap="0.25in" padding-top="6pt" padding-left="6pt" padding-right="6pt" padding-bottom="6pt" margin-top="0.7in" margin-left="0.7in" margin-right="0.7in" margin-bottom="0.7in"/>
<fo:region-before region-name="xsl-region-before" display-align="after" extent="0.7in" padding-top="6pt" padding-left="0.7in" padding-right="0.7in" padding-bottom="6pt"/>
<fo:region-after region-name="xsl-region-after" display-align="before" extent="0.7in" padding-top="6pt" padding-left="0.7in" padding-right="0.7in" padding-bottom="6pt"/>
</fo:simple-page-master>
<fo:page-sequence-master master-name="default-sequence">
<fo:repeatable-page-master-reference master-reference="all-pages"/>
</fo:page-sequence-master>
</fo:layout-master-set>
<fo:page-sequence master-reference="default-sequence">
<fo:flow flow-name="xsl-region-body" font-size="12pt" font-family="Times">
<fo:block border="1pt solid red" xf:annotation-reference="7">Signed document</fo:block>
</fo:flow>
</fo:page-sequence>
</fo:root>
In this example, the reference on the fo:root will generate a singature and the block will become a visible clickable signature in the generated PDF file.
The following traits apply to the xf:signature annotation property: name, location, reason, title, certificate-serial-number, certificate-issuer, time-stamp.
See also the Managing Server Certificates section.