Existing PDF documents are managed by PentaPDF Editor.
To digitally sign or countersign an existing PDF document do the following:
Open the PDF file you wish to sign in PentaPDF Editor.
Right-click on the preview area and select
Sign from the context menu OR
choose Sign from the Sign
menu.
This will open the PentaPDF Options Screen with the
Signature Tab already
opened. It is here where you'll select the Digital Signature you wish to use and
set all other options related to digital signing. See also the
PentaPDF Editor
Tutorial for Digitally Signing PDFs using PentaPDF Editor to
learn more about this screen.
Fill in the Signature Tab according to your needs and click the
OK button.
The next step(s) will depend on whether you chose to sign your document
using a) an invisible or b) a
visible signature:
a) Using an invisible Signature:
If you have decided to sign your PDF document with a signature that won't
be visible in the document,
all that's left to do is to save and close the document. The PDF
document will be saved with its invisible signature and the document
will be verifiable based on this Digital Signature. There will be no
gaphical reference on the PDF page or pages but the Digital Signature
will be present and inidicated by the Security flag "Show Signature"
when viewing the PDF, e. g. using Adobe Reader.
b) Using a visible Signature:
If you have chosen to add a visible signature to your PDF document,
you'll be prompted by a message to indicate in the Editor program where you
want the image of your digital signature to appear in the document:
In the preview area select the page and the position
where you want the
digital signature to be applied:
You can use the page navigation buttons or the page thumbnails on
the Pages tab to go to
the desired page.
The Hand tool
as well as the scroll buttons can be used to move the currently
viewed page around in order to choose the location for the digital signature
place holder.
If needed, you can make the document larger using the zoom features.
Once you have selected the page and position you want the Digital
Signature to be placed, draw the Digital Signature Place Holder:
position the cursor where you want the signature image to start
press the left mouse button
drag your mouse and a dotted line place holder will appear in that area:
As soon as the signature rectangle is drawn, the Preview Screen showing
what the digital signature will look like becomes available.
Press the Sign button to save the signed PDF document. The following
image shows how a visible digital signature will appear when viewing the
digitally signed document using Adobe Acrobat Reader:
as well as the scroll buttons can be used to move the currently
viewed page around in order to choose the location for the digital signature
place holder. 
