Plain LaTeX

library(knitr)
library(kableExtra)
options(knitr.table.format = "html")
dt <- mtcars[1:5, 1:4]

kable(dt, booktabs = T, caption = "Demo Table") %>%
  kable_styling(bootstrap_options = c("striped", "condensed"), 
                latex_options = c("striped", "hold_position"),
                full_width = F) %>%
  add_header_above(c(" ", "Group 1" = 2, "Group 2[note]" = 2)) %>%
  add_footnote(c("table footnote"))
Demo Table
Group 1 Group 2a
mpg cyl disp hp
Mazda RX4 21.0 6 160 110
Mazda RX4 Wag 21.0 6 160 110
Datsun 710 22.8 4 108 93
Hornet 4 Drive 21.4 6 258 110
Hornet Sportabout 18.7 8 360 175
a table footnote

Basic Bootstrap Table

kable(dt, format = "html") %>%
  kable_styling(full_width = F, 
                bootstrap_options = c("striped", "bordered")) %>%
  add_header_above(c(" ", "a" = 2, "b" = 2)) %>%
  add_header_above(c(" ", "c" = 3, "d" = 1))
c d
a b
mpg cyl disp hp
Mazda RX4 21.0 6 160 110
Mazda RX4 Wag 21.0 6 160 110
Datsun 710 22.8 4 108 93
Hornet 4 Drive 21.4 6 258 110
Hornet Sportabout 18.7 8 360 175