Here is what I tried:
using (FileStream stream = new FileStream(FullFileNameDOC, FileMode.Open))
wordDocument = new DocxFormatProvider().Import(stream);
Header header = wordDocument.Sections.First().Headers.Default;
RadFlowDocumentEditor editor = new RadFlowDocumentEditor(header.Document);
using (Stream stream = new FileStream($@"{TemplatesDirectory}FormHeader.PNG", FileMode.Open))
editor.InsertImageInline(stream, "png");
using (FileStream stream = new FileStream(FullFileNameDOC, FileMode.Open))
wordDocument = new DocxFormatProvider().Import(stream);
Header header = wordDocument.Sections.First().Headers.Default;
RadFlowDocumentEditor editor = new RadFlowDocumentEditor(header.Document);
using (Stream stream = new FileStream($@"{TemplatesDirectory}FormHeader.PNG", FileMode.Open))
editor.InsertImageInline(stream, "png");
... this inserts the image but not in the Word document Header; it inserts the image in the Word document Body.
Thanks.