I want to create a pdf with several fillable form boxes but I can't do so with any free PDF software. I can do it in LaTeX but I can't seem to figure out how to get the text in the fillable form to scale its font size to fit. I found the code below and I can make the box whatever size I like, but any text I type inside the box remains a set size and doesn't scale to fit like other PDFs I've seen. I couldn't find anything about it in the hyperref documentation, is there any way to do this or am I SOL?
\usepackage{hyperref}
\begin{document}
\begin{Form}
\noindent
\TextField[name=multilinetextbox, multiline=true, width=\linewidth,height=5in]{}
\end{Form}
\end{document}
\charsize = 12pt
. (source)