Still not sure...

It's very subtle... a very gentle sensation at first, and may vary from person to person

Some people do not feel anything at first... but it may come in time
and what is felt varies from a gentle cool sensation in the centre of the palms
to a strong unmistakable flow rushing across the hands
to a mixture of 'pins & needles' or other sensations

If you want to find out more, you can visit a local meeting in your area by contacting...

http://www.sahajayoga.org/worldwidecontacts