Flag too large. Shortcode placement in WordPress?

Hello,
Thank you for this plugin. I really like it.
However, even with the flag size set to “small” in the widget settings, it (and the padding surrounding it above and beneath) is too large for my top menu.
I have seen other support responses to this suggesting to put the following line to correct this:

[woo_multi_currency_layout5 flag_size=’0.6′]

Can you tell me exactly where this is to be placed in WordPress? Does it go in the Customer CSS section of your Multi Currency plugin? Please advise.
Thank you.