Some of us did our/their teaching practice in rural areas.
I would say that. I don't think many would object, and I would not care if they did. To me, 'some of us' is close enough in meaning to 'we' to allow this.
I think a sentence such as the following is possible, if clumsy:
1. Some of us did our TP in rural areas, and some of us did their TP in the city.
The first 'some of us' includes the speaker; the second does not.
As I said, it's clumsy. Alternatives would be:
2. Some of us did our TP in rural areas, and some of us did theirs in the city. 3. Some of us did our TP in rural areas, and some in the city.
#3 does not tell us in which group the speaker was. Some people would definitely prefer 'their' in this sentence.