For refind: This is resolved.
As per: https://bbs.archlinux.org/viewtopic.php?pid=1468931#p1468931
Summary:
There are 2 methods:
(a) Add the initrd=.. to the refind_linux.conf file.
(b) If using stanza in refind.conf then
add initrd=<microcode.img>
Both methods work it seems. I can confirm (b) works fine.
g