Thanks to the issue report by yufree and Yihui’s kind work, from version 1.6.10 (development version), knitr starts to support using showtext to change fonts in R plots. To demonstrate its usage, this document itself serves as an example. (Rmd source code)
We first do some setup work, mainly about setting options that control the appearance of the plots. Notice that if you create plots in PNG format (the default format for HTML output), it is strongly recommended to use the CairoPNG device rather than the default png, since the latter one could produce quite ugly plots when using showtext.