We did this sometime ago. To add a font to the dropdown in the RTE: Go to widgets folder Find the RichText.mpk Rename it to RichText.zip Extract contents (using > Open With > Windows Explorer) Go to directory tinymce\themes\advanced and find the file editortemplate.js Open the file with notepad search for string themeadvancedfonts Add new font. In our case we added the following string: Lucinda Sans Unicode=Lucida Sans Unicode,arial,sans-serif;
Zip (using Send to > Compressed folder) the contents again and rename to RichText.mpk again.
Optionally you can add a style to the RTE widget in the modeler to set the default font of the RTE body text. Note that Calibri is a non standard web font.