使用knitr在Markdown中使用多列表的HTML

I've used knitr and LaTeX but I'm thinking of changing to Markdown as this seems more compatible with Word (htlatex and Pandoc work but it's far from comfortable). My current problem is finding an alternative to latex() in the Hmisc package. The only alternative I've found is xtable, but it doesn't seem to create multicolumns.I've used knitr and LaTeX but I'm thinking of c