I have imported the CHR image to XenServer 7 but when it starts up for the first time, although it prints on console the resizing disks message, doing /system resource print shows it’s still using the 128MB partition.
Thats interesting, I am using XenServer 7 as well as CHR images with resized disk without any issues.
https://www.dropbox.com/s/3k6j0pd3kn8zs7t/Screenshot%202017-02-28%2010.49.56.png?dl=0
All I did was imported the VMware image (https://download2.mikrotik.com/routeros/6.37.4/chr-6.37.4.vmdk) then increased the size of the disk and turned it on.