Making partial payments on behalf of participants.
To achieve this your campaign will need to be on the 'Fee Percentage' payment option.
To part charge a participant there will need to be a card on the participants account to charge, this can be done by using the pre-card authorisation see this article to understand how the pre-card authorisation works.
Firstly go to the checkout console and search for the participant you would like to part charge and then click 'Charge Card' as shown below.
Once clicked a popup will appear with the fields to fill in for payment, enter the amount that you would like to charge to the card and then click 'Pay'.