Total sum of columns in R

Question

I am trying to add the row of totals for each column to the following data base:

df <- data.frame(
  c1 = c(1,23,4,34),
  c2 = c(5,32,4,6,67),
  c3 = c(53,2,6,7,9)
)

I tried using below line of codes but doesn't seem to work. I am also looking to find %.

a <- map(df, ~ adorn_totals(df, where = "row"))

Thanks