The Unicode symbol for ₣ is:
U+20A3 FRENCH FRANC SIGN
Libertine is an example for a Unicode font that supports the character:
% lualatex or xelatex
\documentclass{article}
\usepackage{libertineotf}
\begin{document}
^^^^20a3 % ASCII notation
\end{document}
Example for GNU FreeFont:
\documentclass{article}
\usepackage{fontspec}
\begin{document}
\fontspec{FreeSerif.otf}
^^^^20a3
\end{document}
Another example for Times New Roman (from Windows 7):
\documentclass{article}
\usepackage{fontspec}
\begin{document}
\fontspec{times.ttf}
^^^^20a3
\end{document}
\fontspec{Comfortaa-Regular.ttf}% Comfortaa Regular:
\fontspec{OpenSans-Regular.ttf}% Open Sans Regular:
Example for siunitx and pdfLaTeX
If lualatex or pdflatex cannot be used, then the symbol can be included as graphics. The graphics is generated by:
% franc.tex
\nofiles
\documentclass{article}
\usepackage{fontspec}
\begin{document}
\fontspec{FreeSerif.otf}
^^^^20a3
\end{document}
It is compiled via:
$ lualatex franc
$ pdfcrop franc
Then franc-crop.pdf can be used as image for pdfLaTeX:
\documentclass{article}
\usepackage{graphicx}
\usepackage{siunitx}
\DeclareRobustCommand*{\myfranc}{\includegraphics[scale=.1]{franc}}
\DeclareSIUnit{\franc}{\myfranc}
\begin{document}
\SI{123.45}{\franc}
\end{document}
If you are using lualatex or xelatex, then the font can be used directly, e.g.:
\DeclareRobustCommand*{\myfranc}{%
\begingroup
\fontspec{FreeSerif.otf}%
^^^^20a3%
\endgroup
}
Find a good version of the symbol on line or create it yourself by compiling with XeLaTeX or LuaLaTeX the file
\documentclass{standalone}
\usepackage{fontspec}
\setmainfont{DejaVu Sans}
\begin{document}
\symbol{"20AA}
\end{document}
If you call the file NIS.tex, then you'll have NIS.pdf. Then, in your document, you can just say
\usepackage{graphicx}
\DeclareRobustCommand{\NIS}{\includegraphics[height=\fontcharht\font`T]{NIS}}
and use the command normally:
\documentclass{article}
\usepackage{graphicx}
\DeclareRobustCommand{\NIS}{\includegraphics[height=\fontcharht\font`T]{NIS}}
\begin{document}
I paid \NIS 200
\Large I paid \NIS 200
\end{document}
See Where do I place my own .sty or .cls files, to make them available to all my .tex files? for instructions about where to put NIS.pdf in order for it to be available for every document.
Best Answer
With
tikzand little bit of cheating (i.e., usinginkscape2tikz):