pfSense

Inside the DNS Server configuration, you have the option to enable Network Booting and specify several options:

IP of next-serevr
Default bios filename
UEFI 32bit filename
UEFI 64bit filename
root-path string

Here is a snippet from the generated dhcpd.conf:

        next-server 192.168.0.53;
        if option arch = 00:06 {
                filename "snponly.efi";
        } else if option arch = 00:07 {
                filename "snponly.efi";
        } else {
                filename "undionly.kpxe";
        }

However, UEFI 64bit could also be arch 00:09 (verified by using ESXi 6.0 plus an ASUS P8Z77-V motherboard). The code should look like this:

        next-server 192.168.0.53;
        if option arch = 00:06 {
                filename "uefi32.efi";
        } else if option arch = 00:07 {
                filename "uefi64.efi";
        } else if option arch = 00:09 {
                filename "uefi64.efi";
        } else {
                filename "default.pxe";
        }