Yes, it is definitely possible to change the font on the Windows sticky notes in Notezilla .
To do so, right-click on Notezilla tray icon (next to the clock) and choose Preferences --> Note tab. This will let you to set the default sticky note settings which includes color, skin, size, font etc.
To know more in detail, please visit: http://www.conceptworld.com/Notezilla/HelpTopic/Preferences-Note-Tab
To change the font of a particular sticky note, watch this short video: