You can use any JPG, PNG or GIF image as your profile picture, however it needs to be 'hosted' (i.e. stored) somewhere else, and you can enter a link to the image on your ridecount profile.
Any image will be resized down to 100px x 100px, so it's best to set your image to this size.
If you use the free Gravatar service, you can check the 'Use my Gravatar account image' and we will search Gravatar for your registered account email address and retrieve the image.
If you want to remove your profile picture, simply leave the field blank and click 'Change Profile Picture'.