Of course, things have improved in recent years because officially the rule no longer applies unless clearly signposted. But if you see a sign that is a yellow diamond inside a white diamond, this is an indicator that you are on the priority road, until you see it cancelled by a black diagonal line through the sign.
However, in rural areas you will often find that Priorité à droite is still assumed, even if there is no road signage: the safest guidance is to assume that cars coming from the right, as you approach a junction, are not going to stop.
The onus is on the car on the left to slow down, and, if necessary, give way. In the event of a collision, the car approaching from the left will almost certainly take the blame.
Word of advice: keep your eyes open, and your break foot ready, but don’t get hung up about it.
© Terry Marsh