Help needed with RSS

Hi all, i want to add an RSS subscription button to my “Search Result” page.

For example, after a user run a search for specific term, e.g “cats and dogs”

My site’s search result page url will become…
‘ https://www.mysite.com/?s=cats+and+dogs ‘

Now what i want to achieve is to add a RSS subscription button at the bottom of this search result page with the targeted url as…
‘ https://www.mysite.com/?s=cats+and+dogs&feed=rss2 ‘

How to code it so that it will automatically grab the url of the search result page and ADD “&feed=rss2” at the end of it to bring user to the feed subscription page?