Can I use Yocto to build a VF50 image?

I did a build using openembedded but I would like to try also Yocto builds.

Do you guys have the instructions to do that?

You can build a Yocto image folowing the steps below:

mkdir fsl-community-bsp
cd fsl-community-bsp
repo init -u https://github.com/Freescale/fsl-community-bsp-platform -b fido 
repo sync

After sync all the repository, initialize your build

source setup-environment build

To see your machine configuration file run:

ls ../sources/meta-fsl-arm-extra/conf/machine/*.conf -l | grep colibri-vf.conf
-rw-rw-r--. 1 raul raul 1400 Sep 22 12:46 ../sources/meta-fsl-arm-extra/conf/machine/colibri-vf.conf

After that, just change the machine at local.conf file:

vi conf/local.conf
MACHINE ??= 'colibri-vf'

Now you can build the image that best fit for you, just a example:

bitbake core-image-base

You can find these information also in a Blog post, along with detailed instructions how to flash the final image: