If it's one like the Airtronics with two of the same length, then one goes right and one goes left. Again, you can tape it to the sides of the fuselage.

The older Spektrum 7 channel receivers had a short antenna on each side of the receiver. I was somewhat concerned about how strong the exit from the receiver was so I reinforced the antenna at it's base with a short (one inch or so) length of shrink tube that I pushed in some epoxy. That made the base solid. Just look at it and be reasonable with how you put it in. With 2.4 GHz systems and their short antennas, it's tough to mess up.

CGr