Consider how much time you are spending on the 100, and how much more you think you can handle on top of it. 100 really isn't much just for kanji. You're only drawing one character, which shouldn't take you more than 30 seconds in the absolute worst case (excepting the youngest cards, which you might need to think hard about initially). You can get those done in a train ride to work, and the other 100 on the way back. (Another 100 on your lunch break, if you're really ambitious).
As always, if you are able to do more, do more. Don't set artifical limits. You'll know when it's too much when you start to resent it. If you're using Anki, use the graphing feature to see what to expect in the coming days, and modify your new card rate according to how much you plan to do. (It doesn't hurt to push yourself beyond "what you've planned", but it's useful to avoid spiking and eventual accumulation of overwhelming review numbers; the SRSer's two worst enemies).
From: New York, NY Registered: 2009-10-02 Posts: 458 Website
I prefer to keep mine at around 100 per day. I'd rather have fewer than more because it's not really overwhelming if I skip a day here and there and have to make that up the next day, and because I think 15-20 is a good number of new cards per day; too many more than that and I'd lose focus.
An RTK deck is a bit of a different beast compared to other decks. But assuming a 10% forget rate of mature cards, and a fully matured RTK deck. You will always be looking at having around ~200 cards that are young (intervals <28 days). This means that eventually reviews will fall to probably <100 a day. But until you hit that though...Just do what you can.
My sentence deck though (core6k) has on average 200 cards a day. If I miss 2-3 days in a row it climbs to 500. Even after I mature the deck I'm looking at always having around 600 cards I'm constantly cycling due to a ~10% forget curve.
Assuming you are using Anki. You can use the graphs to judge how many cards you will have to review in coming days and the backup that will occur. Use it to determine how much you want to push yourself.