Thanks for the reply.
The problem is that in the same blob field I have text just below the image, so I can't load a TPicture as suggested.
We have been using LOADFROM STRING since Delphi 7 and have never had a problem exporting PDF, but now we are migrating applications to newer versions of Delphi.
The interesting thing is that the RTF is perfectly generated and can save without loss of information, but when exporting to PDF it loses the image that is in the footer.