2D Pytorch tensor doesn't have independent random values
You don't use the parameters "loc" and "scale" the right way. They are not suppose to be tensors. Bellow the right syntax : 

dist = torch.distributions.StudentT(10, 0, 1)
dist = torch.distributions.StudentT(10) # 0 and 1 are the default parameters


Then you can sample multiple values like that :

t = dist.rsample(torch.Size([n,m]))
t = dist.rsample(torch.Size([n]))