Typing the tilde '~' character on a PC keyboard
On U.S. International - PC layout, press Alt-N and then Space

How to find keys in General


Go to Preferences->Keyboard Preferences
Input Sources
Check "Show input menu in menu bar"
Click on the flag in the top menu bar
Show keyboard viewer
Look for "~"
Press Shift, look for ~
Press Alt, look for ~
Press Shift+Alt, look for ~