Petea,
the powder stuff as members say is not worth the trouble i tried it years ago and it did not work.
I have used clonex red gel and it does work sometimes faster and sometimes not faster for me . What i did with the gel was pour it in a shot glass just enought to dip the scion in, coat it and stick scion in premade hole in a pre-wet perlite soil mix and it works.
Also last season i did the exact same with other scion but did not use the gel and they rooted as well BUT like i mention sometimes the gel roots faster sometimes not.
There are several different types of Clonex gel i used the Clonex red as its made for hardwood cutting . It has a high amount of Indole Butyric Acid 8g/L which promotes rooting. Also most plants have that within them which i found interesting.
I would say unless your out to have fun and just want to experiment per say go ahead and try the gel but otherwise i would just root em the way most folks do.
Best Health