\documentclass[11pt]{article}
\begin{document}

\section{Introduction}
<<fitmodel>>=
library(datasets)
data(airquality)
fit <- lm(Ozone ~ Wind + Temp + Solar.R, data = airquality)
@

Here is a table of regression coefficients.\\

<<xtable,results=tex>>=
library(xtable)
xt <- xtable(summary(fit))
print(xt)
@
\end{document}