I use saveWidget function in htmlwidgets to save HTML widgets in R. I got the saved HTML files with width 960 and height 500. 
I am pretty sure that I can resize the widget within knitrOptions parameters but I can not find out the list of the parameters to resize the widget. 
I have tried:
library(htmlwidgets)
saveWidget(htmlplot, file, knitrOptions = list(width = 1200, height = 700)
I also have tried using fig.width, defaultWidth, etc. but none of them are worked. 
How could I resize the widget?
 
    