在bookdown krantz.cls示例中，有以下代码对取消注释以获取6x9的书说：

%%%Uncomment to get 6x9 trim
%%%%\textheight = 43pc
%%%%  %\advance\textheight by \topskip
%%%%\addtolength\textheight{3pt}
%%%%  \textwidth 26pc
%%%%\addtolength\textwidth{.5pt}
%%%% \topmargin0in
%%%%  \oddsidemargin1.1875in
%%%%  \evensidemargin1.1875in
%%%%  \htrim5.05pc
%%%%  \vtrimtop7.7pc
%%%%  \vtrimbot5.44pc
%%%%%  \hoffset-5pt
%%%%  \voffset45pt
%%%%\let\normaltextheight\textheight

尽管这样做，我仍无法将这本书以6x9格式打印为pdf。而是渲染为8.5 x 11

我尝试取消注释以下代码的注释，以得到6x9修剪。