// main code
...
Dim image_ As Byte() = LoadImage("Inventory.image_for_report.png")
Dim imageFilename As String = MigraDocFilenameFromByteArray(image_)
paragraph.AddImage(imageFilename)
...

Private Function LoadImage(ByVal filename As String)
    Try
        Dim assembly = System.Reflection.Assembly.GetExecutingAssembly()
        Using stream_ As UnmanagedMemoryStream = assembly.GetManifestResourceStream(filename)
            Dim count As Long = stream_.Length
            Dim data_(count) As Byte
            stream_.Read(data_, 0, count)
            Return data_
        End Using
    Catch ex As Exception
        Return vbNull
    End Try
End Function

Private Function MigraDocFilenameFromByteArray(ByVal image As Byte())
    Return "base64:" & Convert.ToBase64String(image)
End Function

var renderer = new RtfDocumentRenderer();
renderer.Render(doc, stream, closeStream: false, workingDirectory: null)