How to link (a menu item) to the RSS feed?
If you're using i18n module, and after you have installed module Variable, you should enable the i18n_variable module (one of the i18n submodules that requires the Variable module, among others).

Then navigate to /admin/config/regional/i18n/variable (= the Variables tab within '
Multilingual settings'). There you'll be able to specify all sorts of variables for which you want multi language support enabled also, using an appropriate sub-tab there, such as for "Site information", "Menu settings", etc.). Within sub-tab other, there is also "RSS feed for front page" (=The RSS feed for the front page, default is rss.xml). That "other" sub-tab should be between "Menu Settings" (1st sub-tab) and "Site Information" (3rd sub-tab).

I'd be curious to hear if your issue is resolved after you enable that option (by checking the checkbox).