Adding a formula as a resource in a Flow but getting syntax errors

Hi all,

I'm trying to add a formula as a resource in a Flow and I keep getting syntax errors. It's a really basic formula that will be referenced by an Outcome and is basically going to make the Flow take one of 2 paths depending on whether or not a checkbox on the Account has been checked or not. Many thanks to anyone that can help me. I've already specified the data type to be Boolean and this formula is used in a decision that follows a Get Records element that collects all Account field data from the account record that triggered the Flow.

IF(
{!Get_Account_Details.Ringfenced__c}, 'True'
)

In my decision element, I'm basically going to end the flow with a message if the checkbox is checked and allow the flow to continue on its path, if the checkbox is unchecked.

Any other details needed, please let me know.

Thanks in advance,

Matt