Indentation in R code

I am using emacs-21.3 when writing R functions on Linux debian, and I
am trying to follow the advice i R-exts.pdf (2.1.1) regarding
indentation. That is, I set 'c-default-style' to "bsd" and
'c-basic-offset' to 4. However, while this gives me the intended
indentation in C code, it doesn't change the behavior in R code; I
still get an indentation of size 2. This is my .emacs file after
customization:

 (require 'ess-site)
(custom-set-variables
  ;; custom-set-variables was added by Custom -- don't edit or cut/paste it!
  ;; Your init file should contain only one such instance.
 '(c-basic-offset 4)
 '(c-default-style "bsd"))
(custom-set-faces
  ;; custom-set-faces was added by Custom -- don't edit or cut/paste it!
  ;; Your init file should contain only one such instance.
 )

What is missing in the documentation in 'R-exts.pdf'? Or what have I misssed?

--
GÃ¶ran BrostrÃ¶m