I found one solution which surrounds the src block by
#+LATEX: \scriptsize
#+BEGIN_SRC R
print("This block is in scriptsize")
#+END_SRC R
#+LATEX: \normalize




On Sat, Jun 28, 2014 at 11:09 PM, Shiyuan <gshy2014@gmail.com> wrote:

> Hi,
>    When a src code block is exported to latex-pdf, the src lines sometimes
> are too long to fit in a pdf line. One easy way to handle this problem I
> can think of is to temporarily change font size. What is the best way to do
> that in org model?  Say that if I have two src blocks, I want the first
> code block to be typeset in scriptsize but the second block typeset in
> normalsize .
>
> #+BEGIN_SRC R
> print("This block in scriptsize")
> ......
> #+END
>
> #+BEGIN_SRC R
> print("This block back to normalsize")
> ......
> #+END
>
> Thanks.
>