\RequirePackage{luatex85} % For more recent versions of LuaTeX
\documentclass[12pt]{standalone}
\usepackage{fontspec}
\def\pgfsysdriver{ {{tikzpath}}/pgfsys-dvir.def}
\usepackage{tikz}
\setmainfont[Mapping=text-tex]{Lato Light}
\begin{document}
\selectfont
We can combine normal (\LaTeX{}) text with a Ti{\it k}Z picture.
\begin{tikzpicture}
\path (0, 0) node[circle,minimum size=.5in,fill=blue!20,draw,thick] (x) {\sffamily{R}} 
       (3, 0) node[circle,minimum size=.5in,fill=blue!20,draw,thick] (y) {TikZ!};
\draw[->] (x) .. controls (1, 1) and (2, 1).. (y);
\draw[->] (y) .. controls (2, -1) and (1, -1) .. (x);
\end{tikzpicture}
\end{document}