I think that this is my cleanest formuals to show an image on a form and control the size. I presume from your question that each record will have its own logo, but I may have assumed incorrectly and you in fact want the same logo in every form.
var text FileType = Right(ToText([file attachment2]),".");
Did you get this to work? I have tried to add a picture and the suggested text element but the logo doesn't appear. Only whatever I type in the Text widget.
There are two working solutions below. One uses a formula rich text field (provided by @Mark Shnier (YQC))and the other uses a text form element with HTML enabled (provided by @Laura Thacker). Are you trying to add an image to a form or a dashboard widget?
------------------------------ Adam Keever ------------------------------