Streamed packages must be created with Streaming Composer. There is a chance that an XPF created via SVSAdmin will work properly unmodified, but often it is better to let Streaming Composer fix up issues before attempting to stream. Streaming Composer can open an existing XPF (or VSA) and create a streamable version from it.
Are you planning on just having the SEV agents as part of the "gold" image, or did you want to have some applications already streamed/virtualized on the "gold" image from which every machine instantiates itself?
If the former, you need to install the agents, accept the reboot, then afterward remove HKLM\Software\AS_MACHINE_ID (unique client ID, the SWS client will regenerate a new one if this key is missing at startup). Then shut down and use that as the "gold" image - no packages streamed in the gold image yet. When an image is instanced you them stream the applications, either at boot time with a pre-supplied user name, or at user logon when you know the exact user and the needed applications.
If the latter... well, I'm not sure that is supported. Depending on how the OS virtualizer takes an image of the system you could run into several problems with the streamed/virtualized files and configuration data getting out-of-sync or changed such that the SEV clients won't recognize the files. The folder locations and registry keys I provided above are necessary to be preserved, but you wouldn't want them persistent beyond the "gold" image (across machine instances), or you will have the agents confused with data and layers for which they don't know they are responsible.
Every installation we've seen so far take the former approach and start with an empty cache each time a machine instance spins up.