When creating a custom attachment field  for my estimate

Data Type : Attachment

it says we can

So to test this Data Type custom field 

I added the placeholder in my template

${estimate.cf_attachment}

Then I uploaded a jpg image.

But when I print out my estimate or convert it into a pdf I just see the name of the file I attached

I expected to see the image or a url

How is this supposed to work please?
I would for instance like to add images to my Estimate and see them in the PDF.

Thanks