Old bridge pilings

I bought a bag of orchard ley from Koanga nursery. On the instructions, it mentions mixing it with sand and raking it into the ground. So, passing a local river, I stopped to appropriate some sand.

Old bridge pilings

The ley is a 1 kg bag of seeds.  I've yet to plant it, mainly because I am a little confused.  Do I remove the grass and rake the seed and sand mixture into the soil?  Or do I just rake it into the grass?  As the raking is intended to prevent the birds from getting the seeds, and sweet Jesus do I have lots of birds here, I'm probably going to leave the grass and make them work for the seeds.