mapped macro to on multiple lines?

[Wim R. Crols]

Hi,

How can I apply a macro on a set of selected lines? I have a simple 
mapping under <F4> (aligment of '=' on the same column, but it's not 
really important)

:map <F4> 0f=60i <Esc>D60<Bar>p

and I want to execute it for every line in a Visual Line selection. I 
tried this

:'<,'>normal <F4>

But there was no effect. Is there an alternative, please?

Thank you,
Wim