[R] coxme() random effect syntax

[Justin Montemarano]

Hello:

I would like to run a Cox proportional hazards regression on crayfish 
dislodgement at different water velocities by crayfish size class and 
substrate (rock) type. Additionally, there is a covariate variable, rock 
movement that may be influencing crayfish dislodgment. So...

I have crayfish size class (CFSZCL) and substrate type (SUBSZ) as fixed 
factors influencing the dislodgment of crayfish at different water 
velocities (SLIPVEL). Thus, I am currently using the call:

coxph(Surv(SLIPVEL, FREEDOM) ~ CFSZCL + SUBSZ + CFSZCL:SUBSZ, data = 
data.table)

However, I would like to add rock movement (BEDLOAD) as a random 
co-variate, which is not possible with the coxph() function. Is it 
possible to do so with coxme() in the kinship package? If so, what is 
the proper syntax?

Thanks for any help.

Justin Montemarano