It really depends on how generous you are with the loot. Take a look at your existing characters, how well are they equipped? I don't think you want to load up the new character that well (especially since the party probably still has the deceased character's gear), but for example if your party all has +10 high steel weapons, giving a replacement character something equivalent is just going to help them hold their ground. If the party is really rich, you don't need to give the new character anything, the party should want to spend some of that loot to get them properly equipped so they can contribute -- depends on what kind of players you have though.
Since RMFRP characters will tend to get items from their training packages, a reasonable approach would just be to look at what items they received from their TPs and then scale them up to be close to equivalent items that average party members might have. E.g. a TP might award a +5 or +10 item, but if the party has a lot of +20 items, maybe boost that to +15. Or a TP might award a Daily item with a 1st level spell, consider boosting that to a spell of the character's level.
Personally, I would not start replacement characters so far behind in level, though. Lower level characters are not going to be able to contribute much, which means they won't be called on to do things, which depending on how you award XP might mean they don't get much, leaving them stuck in a vicious spiral of irrelevance. So if you do let them lag, make sure to compensate for that both in terms of earning XP and also giving them some story share.