The old fashioned technique to create icons was simply to crop images to work as icons and provide the same image quality for all sizes.
Everyone online seems to be a little bit obsessed with font icons
In the file you download, unzip it and install the fonts on your computer.
After font is installed, go to Icons page and copy ( or
CTRL+C ) the actual icon (not the unicode)
Paste it into your design application using it’s Text tool. For an example, I’ve highlighted and copied the “ea-pencil” icon, then I pasted it into Photoshop.
CTRL+C / CTRL
You will wind up with a block X like in the picture below.
Highlight the broken font and in the character field change it to “Erana.”