To add font to the manager, follow the steps below:
Go to the website https://fonts.google.com/
Select the fonts required.
For example, we choose Roboto regular 400, Roboto regular 400 italic and Roboto bold 700.
Select the text that include the tag link and the lines with font family like the follow.
Right-click on the selection and then copy.
Paste it to the text field as shown below.
Press the OK button to add it.
Paste From Clipboard button
Paste the information from Google Web Fonts (https://fonts.google.com/) and pressing the OK button will add the selected fonts to the Manager. You can either clicking on the button "Paste From Clipboard" or right-click on the text area and select "Paste" from the context menu.