\def\rbshframe #1#2#3#4{\vbox{\hrule height 0pt%   
 \hbox{\vrule width 0pt\kern -#1pt%              
 \vbox{\kern-#1pt\frame{.3}{#2}{#3}{#4}%      
 \kern-.3pt}%                                 
 \kern 0pt\vrule width #1pt}%
 \hrule height #1pt}}%                    

\rbshframe{4}{10}{23pc}{\box4}