On Partica, custon fonts are added by embedding google fonts into the main publication css style sheet.

When a client asks for a specific font for the article viewer, they will either supply a google font link or can be directed to advise what type of font they want.

Search the font on https://fonts.google.com/ until it shows up.

Based on the specifications, such as font-weight, size, etc,  you will need to select the font in question in order to embed it. In This case we are going with Roboto light 300

We click on select this font, and while on the selected family sidebar, we click on the @import radio button to select the import option.

Doing so allows us to copy the follow: 

@import url('https://fonts.googleapis.com/css2?family=Roboto:wght@300&display=swap');

This needs to be pasted on the publication level css as seen below. It should be pasted at the top of the page. From here it's just a matter of updating the various elememts that use the font.

Elements such as: byline, headline, article.title, imageCaption, sectionheader, subheading, text, article-text and phone-number can have the Roboto font or any font added to them.