Scenario
You are wanting to use the Aptos font in your Exclaimer Signature as it is the new default font across all of Office.
Resolution
The Aptos font isn't currently available for the Exclaimer Signature Designer however our product team are investigating ways to include it. In the meantime there is a temporary workaround for this.
A Font Stack can be used to simulate the Aptos font in your signature.
NOTE: If you use a font stack, the recipient will need Aptos installed on their system in order to view it correctly.
You can also add a custom font on the Exclaimer Signature Designer which allows any downloaded font to be added. This is not recommended as it can cause issues as the signature will be rendered as a bitmap image, Outlook removes hyperlinks in images and Apple devices generally removes images to save space.