Ok the Spells tab is on my list to update, above is one of the reasons.
Until then you can use the Actions tab to do this. (The spells tab I plan to update to work allot like the Actions tab does.) and since Channeling is a Ability not a spell it should really be on the Actions Tab anyway.
1- Create a Ability Section (Call it Channels)
2- Change # of sections to 1
3- Select the Class and do a overnight rest to update the RP number.
4- Name the Section what you want I put Channels
5- Add 2 Actions (1- Heal 2- Harm)
[For Heal]
1-Add Cast Action
2-Change RP to the cost of using the action
3-Add Heal Action and configure the action for heal amount.
[For Harm]
1-Add Cast Action
2-Change RP to the cost of using the action
3-Add Heal Action and configure the action for damage amount and save if applicable.
To the Left of the name you can change that number to How many time a day it can be used.
When you use either one it will report Spent RP and your Current RP will drop.