Change the font of table using kable and/or kableExtra for pdf export

[skhaji]

I have created a shiny app where the user can download a formatted version of a table as a pdf. I have been able to style the table for my needs using kable and kable_extra, but I have not been able to change the font. This is within shiny, but I believe it should work the same if I were exporting to pdf without using RMarkdown.

See the reproducible example below. I have tried defining the font using the html_font parameter in kable_styling, and using the latex_header_includes parameter in save_kable. The code below shows my latest formatting attempts with both, but I have tried many others.

Can you advise how I can change the font?

df <- data.frame(animal = c("cat", "dog", "horse", "lemur"), lifespan = c(15, 12, 25, 37))

x <- kable(df, "latex", booktabs = T, linesep = c("", "", "", "\\hline"), col.names = NULL)  %>%
  add_header_above(c("Animal Lifespans" =2), line = F) %>%
  kable_styling(font_size = 5, full_width = TRUE, html_font = '"Arial Narrow"')

save_kable(x, "~/Downloads/test.pdf")

# I tried adding the font by adding the code below as a parameter to the save_kable function, but get errors 
# latex_header_includes = `c("\\\\usepackage{helvet}", "\\\\renewcommand{\\\\familydefault}{\sfdefault}")`