According to perlfunc:require,

The file is included via the do-FILE mechanism, which is essentially just a variety of "eval".

Returning from an eval does what you want, so go ahead and use return(1) if you like.

Personally, I always like to end my modules with:

1 # end of Foo.pm
[download]

It's hard to miss. It tells you where the end is supposed to be, so you know if you lost the last page of your printout. And leaving off the final semicolon means it's likely not to compile if someone tries to add code after it.