Procedure to build a rockchip compatible image from scratch.

rockchip-bootstrap.txt

sudo gdisk <file> or /dev/<target>
o	// to create new gpt
y
x	// expert menu
l	// change sector alignment
64 
m	// return to main menu
n	// create new partition
1
64	// start at sector 64
34815	// end at sector 34815 (16mb minimum aligned to 2048 sectors)
8300	// linux data, default, can just hit return here
x	// return to expert menu and reset sector alignment to 2048
l
2048
m	// return to main menu
n	// create efi partition
2
34816	// default, just hit return here
128M	// go to 128M from start
EF00	// EFI partition type
n	// create boot partition
3
<num>	// default, just hit return here
256M	// minimum
8300	// default
n
4
<num>	// default start
<num>	// default, go to end
8300	// default, linux
c	// change partition names
1
u-boot
c
2
efi
c
3
boot
c
4
recovery
w	// write the table and exit

Now, at this point, the procedure changes if this is an image or an actual device.

If it's an image, you need to mount it
sudo losetup -f -P <image>	// mount as a loop device to the first available, with partitions
losetup | grep <image> 		// find the loop device assigned

Partitioning is the same for either, the only thing that changes is the device name.
sudo mkfs.fat -F 32 /dev/<loop device>p2 or /dev/<target>2	// partition 2 is /boot/efi
sudo mkfs.ext4 /dev/<loop device>p3 or /dev/<target>3		// partition 3 is /boot
sudo mkfs.ext4 /dev/<loop device>p4 or /dev/<target>4		// partition 4 is recovery