If for some reason you must read the block device using a block size of 16K:

dd if=/mnt/nfs bs=16k | pv -L <rate> > /dev/sda 

Where <rate> is the maximum allowed amount of bytes per second to be transferred, or the maximum allowed amount of kibibytes, mibibytes, gibibytes, [...] per second to be transferred if K, M, G, [...] is specified.

However if you don't really have to read the file using a block size of 16K, just use pv, which can read block devices:

pv -L <rate> /mnt/nfs > /dev/sda  

If for some reason you must read the block device using a block size of 16K:

dd if=/mnt/nfs bs=16k | pv -L rate > /dev/sda 

Where rate is the maximum allowed amount of bytes per second to be transferred, or the maximum allowed amount of kibibytes, mibibytes, gibibytes, [...] per second to be transferred if K, M, G, [...] is specified.

However if you don't really have to read the file using a block size of 16K, just use pv, which can read block devices:

pv -L rate /mnt/nfs > /dev/sda

First of all, you're probably specifying the target directory instead of the target file; the of= option of dd expects a path to the target file, so make sure you're specifying a path to a (non existing) target file:

dd if=/dev/sda of=/mnt/nfs/file bs=16k 

If for some reason you must read the block device using a block size of 16K:

dd if=/dev/sda bs=16k | pv -L <rate> > /mnt/nfs/file 

Where <rate> is the maximum allowed amount of bytes per second to be transferred, or the maximum allowed amount of kibibytes, mibibytes, gibibytes, [...] per second to be transferred if K, M, G, [...] is specified.

However if you don't really have to read the file using a block size of 16K, just use pv, which can read block devices:

pv -L <rate> /dev/sda > /mnt/nfs/file 

If for some reason you must read the block device using a block size of 16K:

dd if=/mnt/nfs bs=16k | pv -L <rate> > /dev/sda 

Where <rate> is the maximum allowed amount of bytes per second to be transferred, or the maximum allowed amount of kibibytes, mibibytes, gibibytes, [...] per second to be transferred if K, M, G, [...] is specified.

However if you don't really have to read the file using a block size of 16K, just use pv, which can read block devices:

pv -L <rate> /mnt/nfs > /dev/sda