I am going to create a Preset for GERD and Barrett's Esophagus but I am not able to determine if it should be a Healing or a Killing preset. Can anyone recommend which to use?

Because of what you have described and because you are undecided about healing or killing, go for healing, especially if the programs are combined together.
A frequency will resonate and do its job where needed, regardless of whether you think it’s healing or killing. A Healing preset can both Heal and Kill. The frequency is the most important variable. It is perfectly ok to use Healing presets for both Killing and Healing programs because these presets are gentle on the body.
Likewise, killing presets can also be used for healing, but these generally put more stress on the body (such as kidneys), so are not recommended for healing purposes. Spooky recommends using a Healing preset for almost all applications, especially when in doubt or new to Rifing. This makes treatments significantly simpler.
Killing presets use settings which make the signal stronger. Sometimes a stronger signal is not desirable, even if the function of a program is to kill. It may actually slow down the healing process.
The best way you can get started without trouble is to use the JW – Healing preset for everything — yes even for killing. This preset uses a square wave which is universal and capable of doing both healing and killing modalities well.
You can find these by going to the Presets Tab in the Spooky2 software and choosing of the following presets depending on what device you are using:
• Shell (Empty) Presets/Contact/Healing (C) – JW
• Shell (Empty) Presets/Plasma/Spooky Plasma Entrainment and Healing (P) – JW
• Shell (Empty) Presets/Remote/Healing (R) - JW

For more details, please check the link:
https://www.facebook.com/groups/spooky2/permalink/1745569795604916/