forwarding "@" to a different domain?

[enigmedia]

Hi All: I have a situation where I need to forward requests for "mydomain.com"
and "www.mydomain.com" to a third party: "mydomain.myshopify.com" (while still
pointing other things like MX records elsewhere).

I realize I can point a CNAME for "WWW" to "mydomain.myshopify.com", but how do
I point "mydomain.com" to this third party if there is no A record to point to?

TIA