change table size latex
usepackage{graphics}
% ...
begin{table}
centering
resizebox{columnwidth}{!}{%
begin{tabular}{r|lll}
multicolumn{1}{r}{}
& multicolumn{1}{l}{Heading 1}
& multicolumn{1}{l}{Heading 2}
& multicolumn{1}{l}{Heading 3} \ cline{2-4}
Row 1 & Cell 1,1 & Cell 1,2 & Cell 1,3 \
Row 2 & Cell 2,1 & Cell 2,2 & Cell 2,3
end{tabular}%
}
end{table}