(If you need help installing the Watch version of MyRadar onto your Apple Watch, check out this article here!)
So long as you are on a Watch face that MyRadar currently supports, you should be able to add MyRadar's complication to the Watch face without any issue! Here's the steps on how to do so:
1. Open the Watch app on your iDevice
2. Tap on one of your Watch's faces to enter that face's settings. For these steps, lets set up the complication on a Modular face
3. Now you'll see a list of locations that complications can be placed on. MyRadar's complication requires some space, so you'll want to go for Watch faces that let you add a complication in the center of the Watch face
NOTE that certain types of complications are available only to Apple Watch Series 4 users. If you have a Series 4, you should be able to access "Graphic Corner" complications, which essentially hug the center clock's sides.
If the complication is not loading any weather data, try opening the app on your iDevice while you have the Watch version open as well. This can force the app to 'resync' the two versions of the app and push the weather data to the Watch.