> Can you give details of line required to specify
> minimum file size to collect.

Yes, using *[<>] wildcards:

-*[<5]
will exclude all files smaller than 5KB

-*.gif*[<5]
will exclude all .gif files smaller than 5KB

-www.foo.com/*.gif*[<5]
will exclude all .gif files at www.foo.com smaller 
than 5KB

-www.foo.com/*.gif*[<5] -www.foo.com/*.gif*[>50]
will exclude all .gif files at www.foo.com smaller 
than 5KB and also files bigger than 50KB