Please remember its a treatment concealer that will be helping your skin so its never going to be as smooth as a normal concealer.
The Conceal & Shield is designed to form a protective 'shell' over the spot so once it dries its not like a normal cosmetic concealer. We recommend once dry applying a thin dusting of your favourite powder or a think scrim of your concealer over the top to concealer the 'shell'.
The huge advantage of the Conceal & Shield for your skin is that once its on you can use other cosmetics over the top without fear of exacerbating your acne as the Conceal & Shield is protecting your skin from further invasion with bacteria from other products.
Did you try shaking the tube? Its a very natural product too so sometimes the ingredients need a good shake to blend them. This may help with the smoothness on application.
Another tip is blend the product more with your fingertip after you have applied it.