If the rivets will be used

WARNING: This page is about a different car, the 2005 Mazda MX-5 Miata. However, it is still accessible from the selected car via links, so may be relevant.

Rivet the rain rail to the top fabric.

Fig 1: Riveting Rain Rail To Top Fabric
Courtesy of MAZDA MOTORS CORP.
Flatten the stem using a hammer.

Fig 2: Flattening Stem Using Hammer
Courtesy of MAZDA MOTORS CORP.