You can't use a RD Gateway Server with Mac's Version of the RDC. There are paid applications for Mac that can like iTap Mobile. The alternative would be to use VPN and then remote in. I show the second one below since SBS 2011 has VPN functionality built in. O snap, look who's got a mac?!
![[Linked Image from ]](/ub/attachments/usergals/2012/06/full-2987-275-mac_os_x_10.7_64_bit_2012_06_05_06_54_14.png)
![[Linked Image from ]](/ub/attachments/usergals/2012/06/full-2987-276-mac_os_x_10.7_64_bit_2012_06_05_06_55_17.png)