I'm applying to the US and Canada for PhDs this cycle, my undergraduate university is very well regarded in my country (UK) and generally in the top 5 for domestic rankings/prestige. Even more so for my undergrad program (Physics), which generally accepts people who very narrowly missed out on Oxford/Cambridge places. However is pretty much unheard of outside of Britain (ranked in the 60s/70s globally). Do I ask my referees to make the relative prestige of my uni clear on my LOR so that admissions committees can understand the context of my grades and experiences?? Or would this be considered too on the nose?

I am preparing to send materials to all of my referees with some advice on how to write LORs for North American applications, which they may not have done before, so I would really like to clarify this before I do so.